152 C Programming Questions and Solutions: Ultimate Master Guide for Exams & Interviews (2026)

Welcome to the most comprehensive 152 C Programming Questions and Solutions master guide. Designed specifically for B.Tech, BCA, MCA, and engineering students preparing for university semester examinations (like MAKAUT), lab vivas, and technical coding interviews (TCS, Wipro, Cognizant, Infosys, LTIMindtree).

NOTE

All 152 programs in this guide are fully tested using GCC under C99/C11 standards. Each program includes full executable source code, explanations of key logic, and exam context.

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Master Syllabus & Unit Quick Index

Unit	Topic Coverage	Question Range	Key Focus Areas
Unit 1	Basics, Data Types, Operators, Control Flow	Q1 – Q41	GCC pipeline, Precedence, if-else, switch-case, leap year, roots, grading
Unit 2	Loops, Series Summation, Pattern Printing	Q42 – Q83	for/while/do-while, prime, Armstrong, Fibonacci, Krishnamurthy, 16+ Patterns
Unit 3	Functions, Storage Classes, Pointers, Arrays	Q84 – Q112	Call by value/ref, static/extern, array ops, 2nd max/min, Adam number
Unit 4	Strings, 2D Matrices, 6 Sorting Algorithms	Q113 – Q143	Matrix math, String without string.h, Bubble/Selection/Insertion/Quick/Merge/Shell Sort
Unit 5	Recursion Mechanics & Call Stack Traces	Q144 – Q150	Stack frames, tail recursion, recursive factorial/fib/GCD/string rev
Unit 6	Structures, Unions & Marksheet System	Q151 – Q152	Struct alignment, padding bytes, student database, MAKAUT grade generator

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Quick Reference Cheatsheets

1. C Operator Precedence Table

Priority	Category	Operators	Associativity
1 (Highest)	Postfix	`()` `[]` `->` `.` `++` (post) `--` (post)	Left to Right
2	Unary	`+` `-` `!` `~` `++` (pre) `--` (pre) `(type)` `*` `&` `sizeof`	Right to Left
3	Multiplicative	`*` `/` `%`	Left to Right
4	Additive	`+` `-`	Left to Right
5	Relational	`<` `<=` `>` `>=`	Left to Right
6	Equality	`==` `!=`	Left to Right
7	Logical AND/OR	`&&` `		`	Left to Right
8 (Lowest)	Assignment	`=` `+=` `-=` `*=` `/=` `%=`	Right to Left

2. Sorting Algorithms Performance Summary

Algorithm	Best Time	Average Time	Worst Time	Auxiliary Space	Stability
Bubble Sort	O(N)	O(N^2)	O(N^2)	O(1)	Stable
Selection Sort	O(N^2)	O(N^2)	O(N^2)	O(1)	Unstable
Insertion Sort	O(N)	O(N^2)	O(N^2)	O(1)	Stable
Quick Sort	O(N \log N)	O(N \log N)	O(N^2)	O(\log N)	Unstable
Merge Sort	O(N \log N)	O(N \log N)	O(N \log N)	O(N)	Stable
Shell Sort	O(N \log N)	O(N^{1.3})	O(N^2)	O(1)	Unstable

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Unit 1: Basics, Operators & Decision Control Flow (Q1 – Q41)

Question 1: Addition

Problem Statement: Write a C program to addition.

1/*
2 * Program #01: Addition
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Standard arithmetic addition program.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int a, b, sum;
12 
13    printf("Enter two numbers: ");
14    scanf("%d %d", &a, &b);
15 
16    sum = a + b;
17 
18    printf("Sum = %d\n", sum);
19 
20    return 0;
21}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_001_addition.c -o prog (add -lm if using <math.h>).

---

Question 2: Subtraction

Problem Statement: Write a C program to subtraction.

1/*
2 * Program #02: Subtraction
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Standard arithmetic subtraction program. C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    int a, b, diff;
10 
11    printf("Enter two numbers: ");
12    scanf("%d %d", &a, &b);
13 
14    diff = a - b;
15 
16    printf("Difference = %d\n", diff);
17 
18    return 0;
19}
20 */
21 
22"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
23 
24int main() {
25    int a, b, diff;
26 
27    printf("Enter two numbers: ");
28    scanf("%d %d", &a, &b);
29 
30    diff = a - b;
31 
32    printf("Difference = %d\n", diff);
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_002_subtraction.c -o prog (add -lm if using <math.h>).

---

Question 3: Multiplication

Problem Statement: Write a C program to multiplication.

1/*
2 * Program #03: Multiplication
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Standard arithmetic multiplication program. C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    int a, b, prod;
10 
11    printf("Enter two numbers: ");
12    scanf("%d %d", &a, &b);
13 
14    prod = a * b;
15 
16    printf("Product = %d\n", prod);
17 
18    return 0;
19}
20 */
21 
22"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
23 
24int main() {
25    int a, b, prod;
26 
27    printf("Enter two numbers: ");
28    scanf("%d %d", &a, &b);
29 
30    prod = a * b;
31 
32    printf("Product = %d\n", prod);
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_003_multiplication.c -o prog (add -lm if using <math.h>).

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Question 4: Division

Problem Statement: Write a C program to division.

1/*
2 * Program #04: Division
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Standard arithmetic division program. C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    float a, b, div;
10 
11    printf("Enter two numbers: ");
12    scanf("%f %f", &a, &b);
13 
14    if (b != 0) {
15        div = a / b;
16        printf("Quotient = %.2f\n", div);
17    } else {
18        printf("Error: Division by zero is not allowed.\n");
19    }
20 
21    return 0;
22}
23 */
24 
25"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
26 
27int main() {
28    float a, b, div;
29 
30    printf("Enter two numbers: ");
31    scanf("%f %f", &a, &b);
32 
33    if (b != 0) {
34        div = a / b;
35        printf("Quotient = %.2f\n", div);
36    } else {
37        printf("Error: Division by zero is not allowed.\n");
38    }
39 
40    return 0;
41}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_004_division.c -o prog (add -lm if using <math.h>).

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Question 5: All mathematical operations consisting of 1 5

Problem Statement: Write a C program to all mathematical operations consisting of 1 5.

1/*
2 * Program #05: All Mathematical Operations(consisting of 1-5)
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Combined operations program. C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    int a, b;
10 
11    printf("Enter two numbers: ");
12    scanf("%d %d", &a, &b);
13 
14    printf("Addition: %d + %d = %d\n", a, b, a + b);
15    printf("Subtraction: %d - %d = %d\n", a, b, a - b);
16    printf("Multiplication: %d * %d = %d\n", a, b, a * b);
17 
18    if (b != 0) {
19        printf("Division: %d / %d = %.2f\n", a, b, (float)a / b);
20    } else {
21        printf("Division: Cannot divide by zero\n");
22    }
23 
24    return 0;
25}
26 */
27 
28"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
29 
30int main() {
31    int a, b;
32 
33    printf("Enter two numbers: ");
34    scanf("%d %d", &a, &b);
35 
36    printf("Addition: %d + %d = %d\n", a, b, a + b);
37    printf("Subtraction: %d - %d = %d\n", a, b, a - b);
38    printf("Multiplication: %d * %d = %d\n", a, b, a * b);
39 
40    if (b != 0) {
41        printf("Division: %d / %d = %.2f\n", a, b, (float)a / b);
42    } else {
43        printf("Division: Cannot divide by zero\n");
44    }
45 
46    return 0;
47}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_005_all_mathematical_operations_consisting_of_1_5.c -o prog (add -lm if using <math.h>).

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Question 6: Swap 2 numbers with variable

Problem Statement: Write a C program to swap 2 numbers with variable.

1/*
2 * Program #06: Swap 2 numbers with variable
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    int a, b, temp;
10 
11    printf("Enter a and b: ");
12    scanf("%d %d", &a, &b);
13 
14    printf("Before swap: a = %d, b = %d\n", a, b);
15 
16    temp = a;
17    a = b;
18    b = temp;
19 
20    printf("After swap: a = %d, b = %d\n", a, b);
21 
22    return 0;
23} int temp = a; a = b; b = temp;
24 */
25 
26"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
27 
28int main() {
29    int a, b, temp;
30 
31    printf("Enter a and b: ");
32    scanf("%d %d", &a, &b);
33 
34    printf("Before swap: a = %d, b = %d\n", a, b);
35 
36    temp = a;
37    a = b;
38    b = temp;
39 
40    printf("After swap: a = %d, b = %d\n", a, b);
41 
42    return 0;
43}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_006_swap_2_numbers_with_variable.c -o prog (add -lm if using <math.h>).

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Question 7: Swap 2 numbers without variable

Problem Statement: Write a C program to swap 2 numbers without variable.

1/*
2 * Program #07: Swap 2 numbers without variable
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: a = a + b; b = a - b; a = a - b;
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int a, b;
12 
13    printf("Enter two numbers: ");
14    scanf("%d %d", &a, &b);
15 
16    printf("Before swap: a = %d, b = %d\n", a, b);
17 
18    a = a + b;
19    b = a - b;
20    a = a - b;
21 
22    printf("After swap: a = %d, b = %d\n", a, b);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_007_swap_2_numbers_without_variable.c -o prog (add -lm if using <math.h>).

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Question 8: Farenheit to celcius

Problem Statement: Write a C program to farenheit to celcius.

1/*
2 * Program #08: Farenheit to Celcius
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    float f, c;
10 
11    printf("Enter temperature in Fahrenheit: ");
12    scanf("%f", &f);
13 
14    c = (f - 32) * 5.0 / 9.0;
15 
16    printf("Temperature in Celsius = %.2f\n", c);
17 
18    return 0;
19} C = (F - 32) * 5.0 / 9.0;
20 */
21 
22"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
23 
24int main() {
25    float f, c;
26 
27    printf("Enter temperature in Fahrenheit: ");
28    scanf("%f", &f);
29 
30    c = (f - 32) * 5.0 / 9.0;
31 
32    printf("Temperature in Celsius = %.2f\n", c);
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_008_farenheit_to_celcius.c -o prog (add -lm if using <math.h>).

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Question 9: Reverse 5 digit number without loop

Problem Statement: Write a C program to reverse 5 digit number without loop.

1/*
2 * Program #09: Reverse 5 digit number without loop
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    int n, rev;
10 
11    printf("Enter a 5-digit number: ");
12    scanf("%d", &n);
13 
14    rev = (n % 10) * 10000 + 
15          (n / 10 % 10) * 1000 + 
16          (n / 100 % 10) * 100 + 
17          (n / 1000 % 10) * 10 + 
18          (n / 10000);
19 
20    printf("Reversed number = %d\n", rev);
21 
22    return 0;
23} rev = (n%10)*10000 + (n/10%10)*1000 + (n/100%10)*100 + (n/1000%10)*10 + (n/10000);
24 */
25 
26"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
27 
28int main() {
29    int n, rev;
30 
31    printf("Enter a 5-digit number: ");
32    scanf("%d", &n);
33 
34    rev = (n % 10) * 10000 + 
35          (n / 10 % 10) * 1000 + 
36          (n / 100 % 10) * 100 + 
37          (n / 1000 % 10) * 10 + 
38          (n / 10000);
39 
40    printf("Reversed number = %d\n", rev);
41 
42    return 0;
43}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_009_reverse_5_digit_number_without_loop.c -o prog (add -lm if using <math.h>).

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Question 10: Max and min of 2 numbers

Problem Statement: Write a C program to max and min of 2 numbers.

1/*
2 * Program #10: Max and Min of 2 numbers
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Use basic if-else logic. C Program
6"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
7 
8int main() {
9    int a, b;
10 
11    printf("Enter two numbers: ");
12    scanf("%d %d", &a, &b);
13 
14    if (a > b) {
15        printf("Max is %d, Min is %d\n", a, b);
16    } else if (b > a) {
17        printf("Max is %d, Min is %d\n", b, a);
18    } else {
19        printf("Both numbers are equal(%d)\n", a);
20    }
21 
22    return 0;
23}
24 */
25 
26"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
27 
28int main() {
29    int a, b;
30 
31    printf("Enter two numbers: ");
32    scanf("%d %d", &a, &b);
33 
34    if (a > b) {
35        printf("Max is %d, Min is %d\n", a, b);
36    } else if (b > a) {
37        printf("Max is %d, Min is %d\n", b, a);
38    } else {
39        printf("Both numbers are equal(%d)\n", a);
40    }
41 
42    return 0;
43}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_010_max_and_min_of_2_numbers.c -o prog (add -lm if using <math.h>).

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Question 11: Max of 3 numbers

Problem Statement: Write a C program to max of 3 numbers.

1/*
2 * Program #11: Max of 3 numbers
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Use nested if-else or logical AND operators.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int a, b, c;
12 
13    printf("Enter three numbers: ");
14    scanf("%d %d %d", &a, &b, &c);
15 
16    if (a >= b && a >= c) {
17        printf("Max is %d\n", a);
18    } else if (b >= a && b >= c) {
19        printf("Max is %d\n", b);
20    } else {
21        printf("Max is %d\n", c);
22    }
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_011_max_of_3_numbers.c -o prog (add -lm if using <math.h>).

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Question 12: If number is ve ve or 0

Problem Statement: Write a C program to if number is ve ve or 0.

1/*
2 * Program #12: If number is +ve, -ve or 0
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Simple relational checking against zero.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12 
13    printf("Enter a number: ");
14    scanf("%d", &n);
15 
16    if (n > 0) {
17        printf("%d is Positive\n", n);
18    } else if (n < 0) {
19        printf("%d is Negative\n", n);
20    } else {
21        printf("The number is Zero\n");
22    }
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_012_if_number_is_ve_ve_or_0.c -o prog (add -lm if using <math.h>).

---

Question 13: If number is divisible by 5 and 11

Problem Statement: Write a C program to if number is divisible by 5 and 11.

1/*
2 * Program #13: If number is divisible by 5 AND 11
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: if (n % 5 == 0 && n % 11 == 0)
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12 
13    printf("Enter a number: ");
14    scanf("%d", &n);
15 
16    if (n % 5 == 0 && n % 11 == 0) {
17        printf("%d is divisible by 5 and 11\n", n);
18    } else {
19        printf("%d is not divisible by 5 and 11\n", n);
20    }
21 
22    return 0;
23}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_013_if_number_is_divisible_by_5_and_11.c -o prog (add -lm if using <math.h>).

---

Question 14: If number is even or odd

Problem Statement: Write a C program to if number is even or odd.

1/*
2 * Program #14: If number is even or odd
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: if (n % 2 == 0)
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12 
13    printf("Enter a number: ");
14    scanf("%d", &n);
15 
16    if (n % 2 == 0) {
17        printf("%d is Even\n", n);
18    } else {
19        printf("%d is Odd\n", n);
20    }
21 
22    return 0;
23}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_014_if_number_is_even_or_odd.c -o prog (add -lm if using <math.h>).

---

Question 15: Check if leap year or not

Problem Statement: Write a C program to check if leap year or not.

1/*
2 * Program #15: Check if leap year or not
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: if ((y % 4 == 0 && y % 100 != 0) || y % 400 == 0)
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int year;
12 
13    printf("Enter a year: ");
14    scanf("%d", &year);
15 
16    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
17        printf("%d is a Leap Year\n", year);
18    } else {
19        printf("%d is not a Leap Year\n", year);
20    }
21 
22    return 0;
23}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_015_check_if_leap_year_or_not.c -o prog (add -lm if using <math.h>).

---

Question 16: Check if alphabet or not

Problem Statement: Write a C program to check if alphabet or not.

1/*
2 * Program #16: Check if alphabet or not
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char c;
12 
13    printf("Enter a character: ");
14    scanf(" %c", &c);
15 
16    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
17        printf("'%c' is an Alphabet\n", c);
18    } else {
19        printf("'%c' is not an Alphabet\n", c);
20    }
21 
22    return 0;
23}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_016_check_if_alphabet_or_not.c -o prog (add -lm if using <math.h>).

---

Question 17: Check is vowel or consonant ifelse

Problem Statement: Write a C program to check is vowel or consonant ifelse.

1/*
2 * Program #17: Check is vowel or consonant - IFELSE
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Check if char is a, e, i, o, u(both cases).
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char c;
12    int isLowercaseVowel, isUppercaseVowel;
13 
14    printf("Enter an alphabet: ");
15    scanf(" %c", &c);
16 
17    isLowercaseVowel = (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u');
18    isUppercaseVowel = (c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U');
19 
20    if (isLowercaseVowel || isUppercaseVowel) {
21        printf("'%c' is a Vowel\n", c);
22    } else {
23        printf("'%c' is a Consonant\n", c);
24    }
25 
26    return 0;
27}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_017_check_is_vowel_or_consonant_ifelse.c -o prog (add -lm if using <math.h>).

---

Question 18: Check is alphabet digit or special character

Problem Statement: Write a C program to check is alphabet digit or special character.

1/*
2 * Program #18: Check is alphabet, digit or special character
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Combine alphabet check with digit check(c >= '0' && c <= '9').
6 */
7 
8 
9int main() {
10    char c;
11 
12    printf("Enter any character: ");
13    scanf(" %c", &c);
14 
15    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
16        printf("'%c' is an Alphabet\n", c);
17    } else if (c >= '0' && c <= '9') {
18        printf("'%c' is a Digit\n", c);
19    } else {
20        printf("'%c' is a Special Character\n", c);
21    }
22 
23    return 0;
24}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_018_check_is_alphabet_digit_or_special_character.c -o prog (add -lm if using <math.h>).

---

Question 19: Check if character is uppercase or lowercase

Problem Statement: Write a C program to check if character is uppercase or lowercase.

1/*
2 * Program #19: Check if character is uppercase or lowercase
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Check ASCII ranges.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char c;
12 
13    printf("Enter an alphabet: ");
14    scanf(" %c", &c);
15 
16    if (c >= 'A' && c <= 'Z') {
17        printf("'%c' is Uppercase\n", c);
18    } else if (c >= 'a' && c <= 'z') {
19        printf("'%c' is Lowercase\n", c);
20    } else {
21        printf("'%c' is not an alphabet\n", c);
22    }
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_019_check_if_character_is_uppercase_or_lowercase.c -o prog (add -lm if using <math.h>).

---

Question 20: Input week day number and print week day name ifelse

Problem Statement: Write a C program to input week day number and print week day name ifelse.

1/*
2 * Program #20: Input week-day number and print week-day name - IFELSE
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Chain of if-else statements(1=Monday, etc).
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int day;
12 
13    printf("Enter weekday number(1-7): ");
14    scanf("%d", &day);
15 
16    if (day == 1) {
17        printf("Monday\n");
18    } else if (day == 2) {
19        printf("Tuesday\n");
20    } else if (day == 3) {
21        printf("Wednesday\n");
22    } else if (day == 4) {
23        printf("Thursday\n");
24    } else if (day == 5) {
25        printf("Friday\n");
26    } else if (day == 6) {
27        printf("Saturday\n");
28    } else if (day == 7) {
29        printf("Sunday\n");
30    } else {
31        printf("Invalid input! Please enter a number between 1 and 7.\n");
32    }
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_020_input_week_day_number_and_print_week_day_name_ifelse.c -o prog (add -lm if using <math.h>).

---

Question 21: Total number of different notes in a given amount

Problem Statement: Write a C program to total number of different notes in a given amount.

1/*
2 * Program #21: Total number of different notes in a given amount
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Divide amount by 2000, 500, 100, etc., and take remainders.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int amount;
12 
13    printf("Enter amount: ");
14    scanf("%d", &amount);
15 
16    int notes[] = {2000, 500, 200, 100, 50, 20, 10, 5, 2, 1};
17    int count = 0;
18 
19    printf("Notes breakdown:\n");
20    for (int i = 0; i < 10; i++) {
21        if (amount >= notes[i]) {
22            count = amount / notes[i];
23            printf("%d Rs notes : %d\n", notes[i], count);
24            amount = amount % notes[i];
25        }
26    }
27 
28    return 0;
29}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_021_total_number_of_different_notes_in_a_given_amount.c -o prog (add -lm if using <math.h>).

---

Question 22: Check angles and verify if triangle is valid

Problem Statement: Write a C program to check angles and verify if triangle is valid.

1/*
2 * Program #22: Check angles and verify if triangle is valid
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: if (a + b + c == 180)
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int a, b, c, sum;
12 
13    printf("Enter three angles of triangle: ");
14    scanf("%d %d %d", &a, &b, &c);
15 
16    sum = a + b + c;
17 
18    if (sum == 180 && a > 0 && b > 0 && c > 0) {
19        printf("The triangle is valid.\n");
20    } else {
21        printf("The triangle is not valid.\n");
22    }
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_022_check_angles_and_verify_if_triangle_is_valid.c -o prog (add -lm if using <math.h>).

---

Question 23: Check if triangle is equilateral or isosceles

Problem Statement: Write a C program to check if triangle is equilateral or isosceles.

1/*
2 * Program #23: Check if triangle is equilateral or isosceles
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Equilateral: a==b && b==c. Isosceles: a==b || b==c || a==c.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int a, b, c;
12 
13    printf("Enter three sides of triangle: ");
14    scanf("%d %d %d", &a, &b, &c);
15 
16    if (a == b && b == c) {
17        printf("Triangle is Equilateral.\n");
18    } else if (a == b || b == c || a == c) {
19        printf("Triangle is Isosceles.\n");
20    } else {
21        printf("Triangle is Scalene.\n");
22    }
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_023_check_if_triangle_is_equilateral_or_isosceles.c -o prog (add -lm if using <math.h>).

---

Question 24: Find roots of quadratic equation

Problem Statement: Write a C program to find roots of quadratic equation.

1/*
2 * Program #24: Find roots of quadratic equation
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Calculate discriminant(b*b - 4*a*c).
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><math.h>
10 
11int main() {
12    float a, b, c, discriminant, root1, root2;
13 
14    printf("Enter coefficients a, b and c: ");
15    scanf("%f %f %f", &a, &b, &c);
16 
17    discriminant = b * b - 4 * a * c;
18 
19    if (discriminant > 0) {
20        root1 = (-b + sqrt(discriminant)) / (2 * a);
21        root2 = (-b - sqrt(discriminant)) / (2 * a);
22        printf("Roots are real and distinct: %.2f and %.2f\n", root1, root2);
23    } else if (discriminant == 0) {
24        root1 = root2 = -b / (2 * a);
25        printf("Roots are real and equal: %.2f and %.2f\n", root1, root2);
26    } else {
27        float realPart = -b / (2 * a);
28        float imagPart = sqrt(-discriminant) / (2 * a);
29        printf("Roots are complex: %.2f+%.2fi and %.2f-%.2fi\n", realPart, imagPart, realPart, imagPart);
30    }
31 
32    return 0;
33}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_024_find_roots_of_quadratic_equation.c -o prog (add -lm if using <math.h>).

---

Question 25: Find gross salary given basic salary

Problem Statement: Write a C program to find gross salary given basic salary.

1/*
2 * Program #25: Find gross salary given basic salary
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Salary <= 10K, HRA 10%, DA=15%; Salary <= 20K, HRA=15%, DA=20%; Salary > 20K, HRA 20%, DA=30%;
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    float basic, hra, da, gross;
12 
13    printf("Enter basic salary: ");
14    scanf("%f", &basic);
15 
16    if (basic <= 10000) {
17        hra = basic * 0.10;
18        da = basic * 0.15;
19    } else if (basic <= 20000) {
20        hra = basic * 0.15;
21        da = basic * 0.20;
22    } else {
23        hra = basic * 0.20;
24        da = basic * 0.30;
25    }
26 
27    gross = basic + hra + da;
28    printf("Gross Salary = %.2f\n", gross);
29 
30    return 0;
31}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_025_find_gross_salary_given_basic_salary.c -o prog (add -lm if using <math.h>).

---

Question 26: Input marks and print grade as per makaut regulations

Problem Statement: Write a C program to input marks and print grade as per makaut regulations.

1/*
2 * Program #26: Input marks and print grade as per MAKAUT regulations
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: 100-90 = O; 80-89 = E; 70-79 = A; 60-69 = B; 50-59 = C; 40-49 = D; <40 = F
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int marks;
12 
13    printf("Enter marks: ");
14    scanf("%d", &marks);
15 
16    if (marks >= 90 && marks <= 100) {
17        printf("Grade: O\n");
18    } else if (marks >= 80 && marks <= 89) {
19        printf("Grade: E\n");
20    } else if (marks >= 70 && marks <= 79) {
21        printf("Grade: A\n");
22    } else if (marks >= 60 && marks <= 69) {
23        printf("Grade: B\n");
24    } else if (marks >= 50 && marks <= 59) {
25        printf("Grade: C\n");
26    } else if (marks >= 40 && marks <= 49) {
27        printf("Grade: D\n");
28    } else if (marks < 40 && marks >= 0) {
29        printf("Grade: F\n");
30    } else {
31        printf("Invalid marks entered.\n");
32    }
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_026_input_marks_and_print_grade_as_per_makaut_regulations.c -o prog (add -lm if using <math.h>).

---

Question 27: Take symbol from user and perform operation basic calculator ifelse

Problem Statement: Write a C program to take symbol from user and perform operation basic calculator ifelse.

1/*
2 * Program #27: Take symbol from user and perform operation(basic calculator) - IFELSE
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Chain if-else against '+', '-', '*', '/'.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char op;
12    float num1, num2;
13 
14    printf("Enter operator(+, -, *, /): ");
15    scanf(" %c", &op);
16 
17    printf("Enter two numbers: ");
18    scanf("%f %f", &num1, &num2);
19 
20    if (op == '+') {
21        printf("%.2f + %.2f = %.2f\n", num1, num2, num1 + num2);
22    } else if (op == '-') {
23        printf("%.2f - %.2f = %.2f\n", num1, num2, num1 - num2);
24    } else if (op == '*') {
25        printf("%.2f * %.2f = %.2f\n", num1, num2, num1 * num2);
26    } else if (op == '/') {
27        if (num2 != 0)
28            printf("%.2f / %.2f = %.2f\n", num1, num2, num1 / num2);
29        else
30            printf("Error: Division by zero\n");
31    } else {
32        printf("Invalid operator\n");
33    }
34 
35    return 0;
36}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_027_take_symbol_from_user_and_perform_operation_basic_calculator_ifelse.c -o prog (add -lm if using <math.h>).

---

Question 28: Take symbol from user and perform operation basic calculator switch

Problem Statement: Write a C program to take symbol from user and perform operation basic calculator switch.

1/*
2 * Program #28: Take symbol from user and perform operation(basic calculator) - SWITCH
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Use switch(char).
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char op;
12    float num1, num2;
13 
14    printf("Enter operator(+, -, *, /): ");
15    scanf(" %c", &op);
16 
17    printf("Enter two numbers: ");
18    scanf("%f %f", &num1, &num2);
19 
20    switch(op) {
21        case '+':
22            printf("%.2f + %.2f = %.2f\n", num1, num2, num1 + num2);
23            break;
24        case '-':
25            printf("%.2f - %.2f = %.2f\n", num1, num2, num1 - num2);
26            break;
27        case '*':
28            printf("%.2f * %.2f = %.2f\n", num1, num2, num1 * num2);
29            break;
30        case '/':
31            if (num2 != 0)
32                printf("%.2f / %.2f = %.2f\n", num1, num2, num1 / num2);
33            else
34                printf("Error: Division by zero\n");
35            break;
36        default:
37            printf("Invalid operator\n");
38    }
39 
40    return 0;
41}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_028_take_symbol_from_user_and_perform_operation_basic_calculator_switch.c -o prog (add -lm if using <math.h>).

---

Question 29: Check whether vowel or consonant switch

Problem Statement: Write a C program to check whether vowel or consonant switch.

1/*
2 * Program #29: Check whether vowel or consonant - SWITCH
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Cases for 'a','e','i','o','u'.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char c;
12 
13    printf("Enter an alphabet: ");
14    scanf(" %c", &c);
15 
16    switch(c) {
17        case 'a': case 'e': case 'i': case 'o': case 'u':
18        case 'A': case 'E': case 'I': case 'O': case 'U':
19            printf("'%c' is a Vowel\n", c);
20            break;
21        default:
22            if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
23                printf("'%c' is a Consonant\n", c);
24            else
25                printf("'%c' is not an alphabet\n", c);
26    }
27 
28    return 0;
29}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_029_check_whether_vowel_or_consonant_switch.c -o prog (add -lm if using <math.h>).

---

Question 30: Input week day number and print week day name switch

Problem Statement: Write a C program to input week day number and print week day name switch.

1/*
2 * Program #30: Input week-day number and print week-day name - SWITCH
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Cases 1 to 7.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int day;
12 
13    printf("Enter weekday number(1-7): ");
14    scanf("%d", &day);
15 
16    switch(day) {
17        case 1: printf("Monday\n"); break;
18        case 2: printf("Tuesday\n"); break;
19        case 3: printf("Wednesday\n"); break;
20        case 4: printf("Thursday\n"); break;
21        case 5: printf("Friday\n"); break;
22        case 6: printf("Saturday\n"); break;
23        case 7: printf("Sunday\n"); break;
24        default: printf("Invalid input! Please enter a number between 1 and 7.\n");
25    }
26 
27    return 0;
28}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_030_input_week_day_number_and_print_week_day_name_switch.c -o prog (add -lm if using <math.h>).

---

Question 31: Input m or f and print male of female ifelse

Problem Statement: Write a C program to input m or f and print male of female ifelse.

1/*
2 * Program #31: Input M or F and print Male of Female - IFELSE
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: if (c == 'M') ... else if (c == 'F') ...
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char gender;
12 
13    printf("Enter gender(M/F): ");
14    scanf(" %c", &gender);
15 
16    if (gender == 'M' || gender == 'm') {
17        printf("Male\n");
18    } else if (gender == 'F' || gender == 'f') {
19        printf("Female\n");
20    } else {
21        printf("Invalid input\n");
22    }
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_031_input_m_or_f_and_print_male_of_female_ifelse.c -o prog (add -lm if using <math.h>).

---

Question 32: Input m or f and print male of female switch

Problem Statement: Write a C program to input m or f and print male of female switch.

1/*
2 * Program #32: Input M or F and print Male of Female - SWITCH
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: switch(c) { case 'M': ... case 'F': ... }
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    char gender;
12 
13    printf("Enter gender(M/F): ");
14    scanf(" %c", &gender);
15 
16    switch(gender) {
17        case 'M': case 'm':
18            printf("Male\n");
19            break;
20        case 'F': case 'f':
21            printf("Female\n");
22            break;
23        default:
24            printf("Invalid input\n");
25    }
26 
27    return 0;
28}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_032_input_m_or_f_and_print_male_of_female_switch.c -o prog (add -lm if using <math.h>).

---

Question 33: Input month and print number of days ifelse

Problem Statement: Write a C program to input month and print number of days ifelse.

1/*
2 * Program #33: Input month and print number of days - IFELSE
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Handle leap year logic for February.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int month, year;
12 
13    printf("Enter month(1-12): ");
14    scanf("%d", &month);
15 
16    if (month == 1 || month == 3 || month == 5 || month == 7 || 
17        month == 8 || month == 10 || month == 12) {
18        printf("31 Days\n");
19    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
20        printf("30 Days\n");
21    } else if (month == 2) {
22        printf("Enter year to check leap year: ");
23        scanf("%d", &year);
24        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
25            printf("29 Days(Leap Year)\n");
26        } else {
27            printf("28 Days\n");
28        }
29    } else {
30        printf("Invalid month!\n");
31    }
32 
33    return 0;
34}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_033_input_month_and_print_number_of_days_ifelse.c -o prog (add -lm if using <math.h>).

---

Question 34: Input month and print number of days switch

Problem Statement: Write a C program to input month and print number of days switch.

1/*
2 * Program #34: Input month and print number of days - SWITCH
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Group cases(e.g., case 1: case 3: case 5... print 31).
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int month, year;
12 
13    printf("Enter month(1-12): ");
14    scanf("%d", &month);
15 
16    switch(month) {
17        case 1: case 3: case 5: case 7: case 8: case 10: case 12:
18            printf("31 Days\n");
19            break;
20        case 4: case 6: case 9: case 11:
21            printf("30 Days\n");
22            break;
23        case 2:
24            printf("Enter year to check leap year: ");
25            scanf("%d", &year);
26            if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
27                printf("29 Days(Leap Year)\n");
28            } else {
29                printf("28 Days\n");
30            }
31            break;
32        default:
33            printf("Invalid month!\n");
34    }
35 
36    return 0;
37}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_034_input_month_and_print_number_of_days_switch.c -o prog (add -lm if using <math.h>).

---

Question 35: Electricity bill ifelse

Problem Statement: Write a C program to electricity bill ifelse.

1/*
2 * Program #35: Electricity bill - IFELSE
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: <= 50 units - 50 paise/unit; >50 and <= 150 - 70p/u; >150 and <= 250 - 1.2rs/u; >250 and <= 350 - 1.5rs/u; >350 - 175p/u; NOTE = 20% extra surcharge
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    float units, bill, total_bill;
12 
13    printf("Enter electricity units consumed: ");
14    scanf("%f", &units);
15 
16    if (units <= 50) {
17        bill = units * 0.50;
18    } else if (units <= 150) {
19        bill = (50 * 0.50) + ((units - 50) * 0.70);
20    } else if (units <= 250) {
21        bill = (50 * 0.50) + (100 * 0.70) + ((units - 150) * 1.20);
22    } else if (units <= 350) {
23        bill = (50 * 0.50) + (100 * 0.70) + (100 * 1.20) + ((units - 250) * 1.50);
24    } else {
25        bill = (50 * 0.50) + (100 * 0.70) + (100 * 1.20) + (100 * 1.50) + ((units - 350) * 1.75);
26    }
27 
28    total_bill = bill + (bill * 0.20); // 20% surcharge
29    printf("Total Electricity Bill = Rs. %.2f\n", total_bill);
30 
31    return 0;
32}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_035_electricity_bill_ifelse.c -o prog (add -lm if using <math.h>).

---

Question 36: Electricity bill switch

Problem Statement: Write a C program to electricity bill switch.

1/*
2 * Program #36: Electricity bill - SWITCH
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Switch isn't ideal for ranges, so we create slab identifiers first using if-else.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    float units, bill, total_bill;
12    int slab;
13 
14    printf("Enter electricity units consumed: ");
15    scanf("%f", &units);
16 
17    // Assign slabs since switch requires integers
18    if (units <= 50) slab = 1;
19    else if (units <= 150) slab = 2;
20    else if (units <= 250) slab = 3;
21    else if (units <= 350) slab = 4;
22    else slab = 5;
23 
24    switch(slab) {
25        case 1: 
26            bill = units * 0.50; 
27            break;
28        case 2: 
29            bill = 25 + ((units - 50) * 0.70); 
30            break;
31        case 3: 
32            bill = 95 + ((units - 150) * 1.20); 
33            break;
34        case 4: 
35            bill = 215 + ((units - 250) * 1.50); 
36            break;
37        case 5: 
38            bill = 365 + ((units - 350) * 1.75); 
39            break;
40    }
41 
42    total_bill = bill * 1.20; // adding 20% surcharge
43    printf("Total Electricity Bill = Rs. %.2f\n", total_bill);
44 
45    return 0;
46}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_036_electricity_bill_switch.c -o prog (add -lm if using <math.h>).

---

Question 37: Print all natural numbers in a range

Problem Statement: Write a C program to print all natural numbers in a range.

1/*
2 * Program #37: Print all natural numbers in a range
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Use a while loop.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int start, end;
12 
13    printf("Enter starting number: ");
14    scanf("%d", &start);
15    printf("Enter ending number: ");
16    scanf("%d", &end);
17 
18    int i = start;
19    while (i <= end) {
20        printf("%d ", i);
21        i++;
22    }
23    printf("\n");
24 
25    return 0;
26}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_037_print_all_natural_numbers_in_a_range.c -o prog (add -lm if using <math.h>).

---

Question 38: Print factorial of a given number while loop

Problem Statement: Write a C program to print factorial of a given number while loop.

1/*
2 * Program #38: Print factorial of a given number(While Loop)
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: while(n > 0) { fact *= n; n--; }
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n, i = 1;
12    unsigned long long fact = 1; // using larger capacity type for factorials
13 
14    printf("Enter a positive integer: ");
15    scanf("%d", &n);
16 
17    while (i <= n) {
18        fact *= i;
19        i++;
20    }
21 
22    printf("Factorial of %d = %llu\n", n, fact);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_038_print_factorial_of_a_given_number_while_loop.c -o prog (add -lm if using <math.h>).

---

Question 39: Print sum of all numbers in a range

Problem Statement: Write a C program to print sum of all numbers in a range.

1/*
2 * Program #39: Print sum of all numbers in a range
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Loop and accumulate sum.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int start, end, sum = 0;
12 
13    printf("Enter starting number: ");
14    scanf("%d", &start);
15    printf("Enter ending number: ");
16    scanf("%d", &end);
17 
18    int i = start;
19    while (i <= end) {
20        sum += i;
21        i++;
22    }
23 
24    printf("Sum of numbers from %d to %d = %d\n", start, end, sum);
25 
26    return 0;
27}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_039_print_sum_of_all_numbers_in_a_range.c -o prog (add -lm if using <math.h>).

---

Question 40: Find gross salary given basic salary switch

Problem Statement: Write a C program to find gross salary given basic salary switch.

1/*
2 * Program #40: Find gross salary given basic salary(SWITCH)
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: Salary <= 10K, HRA=10%, DA=15%; Salary <= 20K, HRA=15%, DA= 20%; Salary > 20K, HRA=20%, DA= 30%
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    float basic, hra, da, gross;
12    int category;
13 
14    printf("Enter basic salary: ");
15    scanf("%f", &basic);
16 
17    // Determine category for switch
18    if (basic <= 10000) category = 1;
19    else if (basic <= 20000) category = 2;
20    else category = 3;
21 
22    switch(category) {
23        case 1:
24            hra = basic * 0.10;
25            da = basic * 0.15;
26            break;
27        case 2:
28            hra = basic * 0.15;
29            da = basic * 0.20;
30            break;
31        case 3:
32            hra = basic * 0.20;
33            da = basic * 0.30;
34            break;
35    }
36 
37    gross = basic + hra + da;
38    printf("Gross Salary = %.2f\n", gross);
39 
40    return 0;
41}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_040_find_gross_salary_given_basic_salary_switch.c -o prog (add -lm if using <math.h>).

---

Question 41: Input marks and print grade as per makaut regulations switch

Problem Statement: Write a C program to input marks and print grade as per makaut regulations switch.

1/*
2 * Program #41: Input marks and print grade as per MAKAUT regulations(SWITCH)
3 * Unit 1: Basics, Operators & Control Flow
4 *
5 * Explanation: 100-90=O; 80-89=E; 70-79=A; 60-69=B; 50-59=C; 40-49=D; <40=F
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int marks;
12 
13    printf("Enter marks(0-100): ");
14    scanf("%d", &marks);
15 
16    // Using division by 10 to group ranges into cases
17    switch(marks / 10) {
18        case 10:
19        case 9:
20            printf("Grade: O\n");
21            break;
22        case 8:
23            printf("Grade: E\n");
24            break;
25        case 7:
26            printf("Grade: A\n");
27            break;
28        case 6:
29            printf("Grade: B\n");
30            break;
31        case 5:
32            printf("Grade: C\n");
33            break;
34        case 4:
35            printf("Grade: D\n");
36            break;
37        case 3: case 2: case 1: case 0:
38            if(marks >= 0)
39                printf("Grade: F\n");
40            else
41                printf("Invalid marks\n");
42            break;
43        default:
44            printf("Invalid marks\n");
45    }
46 
47    return 0;
48}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_041_input_marks_and_print_grade_as_per_makaut_regulations_switch.c -o prog (add -lm if using <math.h>).

---

Unit 2: Loops, Series Summation & Pattern Printing (Q42 – Q83)

Question 42: Write a program to print the numbers 1 to 10 using for loop

Problem Statement: Write a C program to write a program to print the numbers 1 to 10 using for loop.

1/*
2 * Program #42: Write a program to print the numbers 1 to 10 using for loop
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 *
6 */
7 
8for(int i=1; i<=10; i++) printf("%d ", i);

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_042_write_a_program_to_print_the_numbers_1_to_10_using_for_loop.c -o prog (add -lm if using <math.h>).

---

Question 43: Factorial of a number using for loop

Problem Statement: Write a C program to factorial of a number using for loop.

1/*
2 * Program #43: Factorial of a number using for loop
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 *
6 */
7 
8for(int i=1; i<=10; i++) printf("%d ", i);

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_043_factorial_of_a_number_using_for_loop.c -o prog (add -lm if using <math.h>).

---

Question 44: Sum of 10 numbers entered by user using for loop

Problem Statement: Write a C program to sum of 10 numbers entered by user using for loop.

1/*
2 * Program #44: Sum of 10 numbers entered by user using for loop
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 *
6 */
7 
8Loop 10 times, scanf, and add to sum.

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_044_sum_of_10_numbers_entered_by_user_using_for_loop.c -o prog (add -lm if using <math.h>).

---

Question 45: Write a program to print the product of 10 numbers using for loop

Problem Statement: Write a C program to write a program to print the product of 10 numbers using for loop.

1/*
2 * Program #45: Write a program to print the product of 10 numbers using for loop
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 *
6 */
7 
8Loop 10 times, scanf, and multiply to prod.

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_045_write_a_program_to_print_the_product_of_10_numbers_using_for_loop.c -o prog (add -lm if using <math.h>).

---

Question 46: Write a program to print the sum of series 1 x x 2 x n

Problem Statement: Write a C program to write a program to print the sum of series 1 x x 2 x n.

1/*
2 * Program #46: Write a program to print the sum of series 1 + x + x^2 + ... + x^n
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Maintain a term variable multiplied by x each iteration.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int x, n;
12    long long sum = 1, term = 1;
13 
14    printf("Enter values for x and n: ");
15    scanf("%d %d", &x, &n);
16 
17    for (int i = 1; i <= n; i++) {
18        term *= x;     // computes x^i
19        sum += term;
20    }
21 
22    printf("Sum of the series = %lld\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_046_write_a_program_to_print_the_sum_of_series_1_x_x_2_x_n.c -o prog (add -lm if using <math.h>).

---

Question 47: Write a program to print the sum of series x x 2 x 3 x n

Problem Statement: Write a C program to write a program to print the sum of series x x 2 x 3 x n.

1/*
2 * Program #47: Write a program to print the sum of series -x + x^2 - x^3 + ... + x^n
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Multiply term by -x each iteration.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int x, n;
12    long long sum = 0, term = 1;
13 
14    printf("Enter values for x and n: ");
15    scanf("%d %d", &x, &n);
16 
17    for (int i = 1; i <= n; i++) {
18        term *= -x;    // Alternate signs and compute power
19        sum += term;
20    }
21 
22    printf("Sum of the alternating series = %lld\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_047_write_a_program_to_print_the_sum_of_series_x_x_2_x_3_x_n.c -o prog (add -lm if using <math.h>).

---

Question 48: Write a program to print the sum of series 1 x 1 x 2 2 x 3 3 x n n

Problem Statement: Write a C program to write a program to print the sum of series 1 x 1 x 2 2 x 3 3 x n n.

1/*
2 * Program #48: Write a program to print the sum of series 1 + x/1! + x^2/2! + x^3/3! + ... + x^n/n!
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: e^x series.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int x, n;
12    double sum = 1.0, term = 1.0;
13 
14    printf("Enter values for x and n: ");
15    scanf("%d %d", &x, &n);
16 
17    for (int i = 1; i <= n; i++) {
18        term = term * x / i;  // Compute next term dynamically
19        sum += term;
20    }
21 
22    printf("Sum of the e^x series = %.4lf\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_048_write_a_program_to_print_the_sum_of_series_1_x_1_x_2_2_x_3_3_x_n_n.c -o prog (add -lm if using <math.h>).

---

Question 49: Write a program to print the sum of series 1 x 1 x 2 2 x 3 3 x n n

Problem Statement: Write a C program to write a program to print the sum of series 1 x 1 x 2 2 x 3 3 x n n.

1/*
2 * Program #49: Write a program to print the sum of series 1 - x/1! + x^2/2! - x^3/3! + ... + x^n/n!
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Alternating sign e^x series.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int x, n;
12    double sum = 1.0, term = 1.0;
13 
14    printf("Enter values for x and n: ");
15    scanf("%d %d", &x, &n);
16 
17    for (int i = 1; i <= n; i++) {
18        term = term * (-x) / i;  // Compute next term dynamically with alternating sign
19        sum += term;
20    }
21 
22    printf("Sum of the alternating series = %.4lf\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_049_write_a_program_to_print_the_sum_of_series_1_x_1_x_2_2_x_3_3_x_n_n.c -o prog (add -lm if using <math.h>).

---

Question 50: Calculate result of series 1 1 2 1 2 3 1 2 n

Problem Statement: Write a C program to calculate result of series 1 1 2 1 2 3 1 2 n.

1/*
2 * Program #50: Calculate result of series 1 + (1+2) + (1+2+3) + ... + (1+2+...+n)
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Triangular numbers sum.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n, inner_sum = 0, total_sum = 0;
12 
13    printf("Enter the value of n: ");
14    scanf("%d", &n);
15 
16    for (int i = 1; i <= n; i++) {
17        inner_sum += i;          // Sum up to current i (e.g., 1+2+3)
18        total_sum += inner_sum;  // Add to the grand total
19    }
20 
21    printf("Sum of the series = %d\n", total_sum);
22 
23    return 0;
24}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_050_calculate_result_of_series_1_1_2_1_2_3_1_2_n.c -o prog (add -lm if using <math.h>).

---

Question 51: Write a program to print the sum of series 1 11 111 1111

Problem Statement: Write a C program to write a program to print the sum of series 1 11 111 1111.

1/*
2 * Program #51: Write a program to print the sum of series 1 + 11 + 111 + 1111 + ...
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: term = term * 10 + 1.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12    long long term = 0, sum = 0;
13 
14    printf("Enter the number of terms: ");
15    scanf("%d", &n);
16 
17    for (int i = 1; i <= n; i++) {
18        term = term * 10 + 1;  // Generates 1, 11, 111, etc.
19        sum += term;
20    }
21 
22    printf("Sum of the series = %lld\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_051_write_a_program_to_print_the_sum_of_series_1_11_111_1111.c -o prog (add -lm if using <math.h>).

---

Question 52: Write a program to check whether a number is prime number or not

Problem Statement: Write a C program to write a program to check whether a number is prime number or not.

1/*
2 * Program #52: Write a program to check whether a number is prime number or not
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Loop up to n/2 or sqrt(n) and check divisibility.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n, isPrime = 1;
12 
13    printf("Enter a positive integer: ");
14    scanf("%d", &n);
15 
16    if (n <= 1) {
17        isPrime = 0;
18    } else {
19        for (int i = 2; i <= n / 2; i++) {
20            if (n % i == 0) {
21                isPrime = 0;
22                break;
23            }
24        }
25    }
26 
27    if (isPrime) {
28        printf("%d is a Prime Number\n", n);
29    } else {
30        printf("%d is not a Prime Number\n", n);
31    }
32 
33    return 0;
34}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_052_write_a_program_to_check_whether_a_number_is_prime_number_or_not.c -o prog (add -lm if using <math.h>).

---

Question 53: Write a program to print the total numbers of odd and even numbers in range and add them separately

Problem Statement: Write a C program to write a program to print the total numbers of odd and even numbers in range and add them separately.

1/*
2 * Program #53: Write a program to print the total numbers of odd and even numbers in range and add them separately
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Use modulo 2 in a loop to increment respective counters.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int start, end, evenCount = 0, oddCount = 0, evenSum = 0, oddSum = 0;
12 
13    printf("Enter start and end of range: ");
14    scanf("%d %d", &start, &end);
15 
16    for (int i = start; i <= end; i++) {
17        if (i % 2 == 0) {
18            evenCount++;
19            evenSum += i;
20        } else {
21            oddCount++;
22            oddSum += i;
23        }
24    }
25 
26    printf("Even Numbers: Total = %d, Sum = %d\n", evenCount, evenSum);
27    printf("Odd Numbers: Total = %d, Sum = %d\n", oddCount, oddSum);
28 
29    return 0;
30}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_053_write_a_program_to_print_the_total_numbers_of_odd_and_even_numbers_in_range_and_add_them_separately.c -o prog (add -lm if using <math.h>).

---

Question 54: Write a program to calculate if a number is armstrong or not within a range

Problem Statement: Write a C program to write a program to calculate if a number is armstrong or not within a range.

1/*
2 * Program #54: Write a program to calculate if a number is armstrong or not within a range
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: 153 = 1^3 + 5^3 + 3^3
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><math.h>
10 
11int main() {
12    int start, end, temp, rem, sum;
13 
14    printf("Enter start and end of range: ");
15    scanf("%d %d", &start, &end);
16 
17    printf("Armstrong numbers between %d and %d are:\n", start, end);
18    for (int i = start; i <= end; i++) {
19        temp = i;
20        sum = 0;
21 
22        while (temp > 0) {
23            rem = temp % 10;
24            sum += rem * rem * rem; // Assuming standard 3-digit Armstrong for simplicity
25            temp /= 10;
26        }
27 
28        if (sum == i) {
29            printf("%d ", i);
30        }
31    }
32    printf("\n");
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_054_write_a_program_to_calculate_if_a_number_is_armstrong_or_not_within_a_range.c -o prog (add -lm if using <math.h>).

---

Question 55: Write a program to find out the fibonacci series within a range

Problem Statement: Write a C program to write a program to find out the fibonacci series within a range.

1/*
2 * Program #55: Write a program to find out the fibonacci series within a range
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: 1, 1, 2, 3, 5, 8, 13, 21,...
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int start, end;
12    int a = 0, b = 1, next = 0;
13 
14    printf("Enter start and end of range: ");
15    scanf("%d %d", &start, &end);
16 
17    printf("Fibonacci numbers between %d and %d:\n", start, end);
18 
19    while (next <= end) {
20        if (next >= start) {
21            printf("%d ", next);
22        }
23        a = b;
24        b = next;
25        next = a + b;
26    }
27    printf("\n");
28 
29    return 0;
30}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_055_write_a_program_to_find_out_the_fibonacci_series_within_a_range.c -o prog (add -lm if using <math.h>).

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Question 56: Write a program to find out the non fibonacci nos within a range

Problem Statement: Write a C program to write a program to find out the non fibonacci nos within a range.

1/*
2 * Program #56: Write a program to find out the non fibonacci nos within a range
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Generate fibonacci numbers and print the gaps between them.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int start, end;
12    int a = 0, b = 1, c = 0;
13 
14    printf("Enter start and end of range: ");
15    scanf("%d %d", &start, &end);
16 
17    printf("Non-Fibonacci numbers between %d and %d:\n", start, end);
18 
19    for (int i = start; i <= end; i++) {
20        // Advance fibonacci until it meets or exceeds current number i
21        while (c < i) {
22            a = b;
23            b = c;
24            c = a + b;
25        }
26 
27        // If current number i is not equal to fibonacci number c, it's non-fibonacci
28        if (c != i) {
29            printf("%d ", i);
30        }
31    }
32    printf("\n");
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_056_write_a_program_to_find_out_the_non_fibonacci_nos_within_a_range.c -o prog (add -lm if using <math.h>).

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Question 57: Write a program to find out if a number is palindrome or not

Problem Statement: Write a C program to write a program to find out if a number is palindrome or not.

1/*
2 * Program #57: Write a program to find out if a number is palindrome or not
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: 585, 13431
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n, reversed = 0, remainder, original;
12 
13    printf("Enter an integer: ");
14    scanf("%d", &n);
15 
16    original = n;
17 
18    while (n != 0) {
19        remainder = n % 10;
20        reversed = reversed * 10 + remainder;
21        n /= 10;
22    }
23 
24    if (original == reversed) {
25        printf("%d is a Palindrome.\n", original);
26    } else {
27        printf("%d is not a Palindrome.\n", original);
28    }
29 
30    return 0;
31}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_057_write_a_program_to_find_out_if_a_number_is_palindrome_or_not.c -o prog (add -lm if using <math.h>).

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Question 58: Write a program to reverse a number for loop

Problem Statement: Write a C program to write a program to reverse a number for loop.

1/*
2 * Program #58: Write a program to reverse a number(for loop)
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Extract digits using % 10.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n, reversed = 0;
12 
13    printf("Enter an integer: ");
14    scanf("%d", &n);
15 
16    for (int temp = n; temp != 0; temp /= 10) {
17        reversed = reversed * 10 + (temp % 10);
18    }
19 
20    printf("Reversed Number = %d\n", reversed);
21 
22    return 0;
23}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_058_write_a_program_to_reverse_a_number_for_loop.c -o prog (add -lm if using <math.h>).

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Question 59: Write a program to find out if a number is krishnamurty number or not

Problem Statement: Write a C program to write a program to find out if a number is krishnamurty number or not.

1/*
2 * Program #59: Write a program to find out if a number is Krishnamurty Number or not
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: 145 = 1! + 4! + 5!
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n, temp, rem, sum = 0, fact;
12 
13    printf("Enter a number: ");
14    scanf("%d", &n);
15 
16    temp = n;
17    while (temp > 0) {
18        rem = temp % 10;
19        fact = 1;
20        // Calculate factorial of the digit
21        for (int i = 1; i <= rem; i++) {
22            fact *= i;
23        }
24        sum += fact;
25        temp /= 10;
26    }
27 
28    if (sum == n) {
29        printf("%d is a Krishnamurthy Number\n", n);
30    } else {
31        printf("%d is not a Krishnamurthy Number\n", n);
32    }
33 
34    return 0;
35}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_059_write_a_program_to_find_out_if_a_number_is_krishnamurty_number_or_not.c -o prog (add -lm if using <math.h>).

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Question 60: Write a program to find out the binary to decimal and vice versa

Problem Statement: Write a C program to write a program to find out the binary to decimal and vice versa.

1/*
2 * Program #60: Write a program to find out the binary to decimal and vice versa
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Use base 2 multiplication and modulo operations.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><math.h>
10 
11int main() {
12    int choice;
13    long long n;
14 
15    printf("1. Binary to Decimal\n2. Decimal to Binary\nEnter choice: ");
16    scanf("%d", &choice);
17 
18    printf("Enter the number: ");
19    scanf("%lld", &n);
20 
21    if (choice == 1) {
22        int dec = 0, i = 0, rem;
23        while (n != 0) {
24            rem = n % 10;
25            n /= 10;
26            dec += rem * pow(2, i);
27            ++i;
28        }
29        printf("Decimal equivalent = %d\n", dec);
30    } 
31    else if (choice == 2) {
32        long long bin = 0;
33        int rem, i = 1;
34        while (n != 0) {
35            rem = n % 2;
36            n /= 2;
37            bin += rem * i;
38            i *= 10;
39        }
40        printf("Binary equivalent = %lld\n", bin);
41    } else {
42        printf("Invalid choice!\n");
43    }
44 
45    return 0;
46}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_060_write_a_program_to_find_out_the_binary_to_decimal_and_vice_versa.c -o prog (add -lm if using <math.h>).

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Question 61: Write a program to calculate the gcd of two numbers

Problem Statement: Write a C program to write a program to calculate the gcd of two numbers.

1/*
2 * Program #61: Write a program to calculate the GCD of two numbers
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Euclidean algorithm.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int a, b, temp;
12 
13    printf("Enter two numbers: ");
14    scanf("%d %d", &a, &b);
15 
16    printf("GCD of %d and %d is ", a, b);
17 
18    // Euclidean algorithm
19    while (b != 0) {
20        temp = b;
21        b = a % b;
22        a = temp;
23    }
24 
25    printf("%d\n", a);
26 
27    return 0;
28}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_061_write_a_program_to_calculate_the_gcd_of_two_numbers.c -o prog (add -lm if using <math.h>).

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Question 62: Write a program to print the sum of series 1 1 2 1 3 1 n

Problem Statement: Write a C program to write a program to print the sum of series 1 1 2 1 3 1 n.

1/*
2 * Program #62: Write a program to print the sum of series 1 + 1/2 + 1/3 + ... + 1/n
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Harmonic series sum.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12    float sum = 0.0;
13 
14    printf("Enter the value of n: ");
15    scanf("%d", &n);
16 
17    for (int i = 1; i <= n; i++) {
18        sum += 1.0 / i;
19    }
20 
21    printf("Sum of the harmonic series = %f\n", sum);
22 
23    return 0;
24}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_062_write_a_program_to_print_the_sum_of_series_1_1_2_1_3_1_n.c -o prog (add -lm if using <math.h>).

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Question 63: Write a program to print the sum of series 1 2 2 3 3 n n

Problem Statement: Write a C program to write a program to print the sum of series 1 2 2 3 3 n n.

1/*
2 * Program #63: Write a program to print the sum of series 1 + 2^2 + 3^3 + ... + n^n
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Requires pow() function from math.h.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><math.h>
10 
11int main() {
12    int n;
13    long long sum = 0;
14 
15    printf("Enter the value of n: ");
16    scanf("%d", &n);
17 
18    for (int i = 1; i <= n; i++) {
19        sum += pow(i, i);
20    }
21 
22    printf("Sum of the series = %lld\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_063_write_a_program_to_print_the_sum_of_series_1_2_2_3_3_n_n.c -o prog (add -lm if using <math.h>).

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Question 64: Write a program to print the sum of series 1 2 2 3 3 4 n 1 n

Problem Statement: Write a C program to write a program to print the sum of series 1 2 2 3 3 4 n 1 n.

1/*
2 * Program #64: Write a program to print the sum of series 1/2 + 2/3 + 3/4 + ... + (n-1)/n
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Fractional series addition.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12    float sum = 0.0;
13 
14    printf("Enter the value of n: ");
15    scanf("%d", &n);
16 
17    for (int i = 1; i < n; i++) {
18        sum += (float)i / (i + 1);
19    }
20 
21    printf("Sum of the series = %f\n", sum);
22 
23    return 0;
24}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_064_write_a_program_to_print_the_sum_of_series_1_2_2_3_3_4_n_1_n.c -o prog (add -lm if using <math.h>).

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Question 65: Write a program to print the sum of series 1 2 2 2 3 3 3 n n n

Problem Statement: Write a C program to write a program to print the sum of series 1 2 2 2 3 3 3 n n n.

1/*
2 * Program #65: Write a program to print the sum of series 1 + 2^2/2 + 3^3/3 + ... + n^n/n
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Simplify to 1 + 2 + 3^2 + ... + n^(n-1).
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><math.h>
10 
11int main() {
12    int n;
13    double sum = 0.0;
14 
15    printf("Enter the value of n: ");
16    scanf("%d", &n);
17 
18    for (int i = 1; i <= n; i++) {
19        sum += pow(i, i) / i; // Equivalent to pow(i, i-1)
20    }
21 
22    printf("Sum of the series = %.2lf\n", sum);
23 
24    return 0;
25}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_065_write_a_program_to_print_the_sum_of_series_1_2_2_2_3_3_3_n_n_n.c -o prog (add -lm if using <math.h>).

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Question 66: Write a program to print the sum of series x x 3 3 x 5 5 x 7 7

Problem Statement: Write a C program to write a program to print the sum of series x x 3 3 x 5 5 x 7 7.

1/*
2 * Program #66: Write a program to print the sum of series x - x^3/3! + x^5/5! - x^7/7! + ...
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: sin(x) Maclaurin series approximation.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int x, n;
12    double sum, term;
13 
14    printf("Enter value of x and n: ");
15    scanf("%d %d", &x, &n);
16 
17    term = x;
18    sum = x;
19 
20    for (int i = 1; i < n; i++) {
21        term = term * -1 * x * x / ((2 * i) * (2 * i + 1));
22        sum += term;
23    }
24 
25    printf("Sum of the sin(x) series = %.4lf\n", sum);
26 
27    return 0;
28}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_066_write_a_program_to_print_the_sum_of_series_x_x_3_3_x_5_5_x_7_7.c -o prog (add -lm if using <math.h>).

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Question 67: Write a program to repeatedly divide a number by 2 and print the quotient

Problem Statement: Write a C program to write a program to repeatedly divide a number by 2 and print the quotient.

1/*
2 * Program #67: Write a program to repeatedly divide a number by 2 and print the quotient
3 * Unit 2: Loops, Series & Number Patterns
4 *
5 * Explanation: Use a while loop until n == 0.
6 */
7 
8"text-[#cf222e] dark:text-[#c586c0] font-semibold">#include "text-[#0a3069] dark:text-[#ce9178]"><stdio.h>
9 
10int main() {
11    int n;
12 
13    printf("Enter a number: ");
14    scanf("%d", &n);
15 
16    while (n > 0) {
17        n = n / 2;
18        printf("Quotient = %d\n", n);
19    }
20 
21    return 0;
22}

NOTE

Key Takeaway: Always handle edge cases like invalid input or zero values. Compile with gcc prog_067_write_a_program_to_repeatedly_divide_a_number_by_2_and_print_the_quotient.c -o prog (add -lm if using <math.h>).

---