Why Practice Programs?

C becomes strong only through regular program practice. The following 50 programs cover basics, loops, arrays, strings, pointers, structures, files and data structures.

50 Important C Programs

1. 1. Hello World
2. 2. Sum of two numbers
3. 3. Even or odd
4. 4. Largest of two numbers
5. 5. Largest of three numbers
6. 6. Leap year
7. 7. Factorial
8. 8. Fibonacci series
9. 9. Prime number
10. 10. Palindrome number
11. 11. Armstrong number
12. 12. Reverse number
13. 13. Sum of digits
14. 14. Multiplication table
15. 15. Swap two numbers
16. 16. Simple calculator
17. 17. Area of circle
18. 18. Celsius to Fahrenheit
19. 19. Array sum
20. 20. Array maximum
21. 21. Array minimum
22. 22. Linear search
23. 23. Binary search
24. 24. Bubble sort
25. 25. Selection sort
26. 26. Insertion sort
27. 27. Matrix addition
28. 28. Matrix multiplication
29. 29. String length
30. 30. String reverse
31. 31. String palindrome
32. 32. Count vowels
33. 33. Copy string
34. 34. Compare strings
35. 35. Function for factorial
36. 36. Recursion factorial
37. 37. Recursion Fibonacci
38. 38. Pointer swap
39. 39. Pointer array sum
40. 40. Structure student record
41. 41. Union example
42. 42. Enum week days
43. 43. File write
44. 44. File read
45. 45. Append file
46. 46. Linked list insert
47. 47. Stack using array
48. 48. Queue using array
49. 49. Dynamic memory array
50. 50. Command line sum

Sample Program: Prime Number

#include <stdio.h>

int main() {
    int n, flag = 1;
    printf("Enter number: ");
    scanf("%d", &n);

    if(n <= 1) flag = 0;
    for(int i = 2; i * i <= n; i++) {
        if(n % i == 0) {
            flag = 0;
            break;
        }
    }

    if(flag) printf("Prime");
    else printf("Not Prime");
    return 0;
}

Sample Program: Reverse Number

int n = 1234, rev = 0;
while(n > 0) {
    rev = rev * 10 + n % 10;
    n = n / 10;
}
printf("Reverse = %d", rev);

Practice Tips

• First write logic in plain language
• Then write algorithm or flow steps
• Code without copying after understanding
• Run with different test cases
• Keep a notebook of common mistakes