Top 50 C Coding Interview Questions and Answers (2024)

C is the most popular programming language developed by Dennis Ritchie at the Bell Laboratories in 1972 to develop the UNIX operating systems. It is a general-purpose and procedural programming language. It is faster than the languages like Java and Python. C is the most used language in top companies such as LinkedIn, Microsoft, Opera, Meta, and NASA because of its performance. To get into these companies and other software companies, you need to master some important C coding questions to crack their C Online Assessment round and coding interview.

C-coding-Questions---Answers

C Coding Interview Questions and Answers

This article on C Coding Interview Questions offers a comprehensive collection of practice questions suitable for both beginners and advanced learners.

List of 50 C Coding Interview Questions and Answer

Here is a list of 50 C coding interview questions and answers:

1. Find the largest number among the three numbers.

Output

2. Write a Program to check whether a number is prime or not.

Output

Is a Prime Number

3. Write a C program to calculate Compound Interest.

Output

Compound Interest is : 714.830823

4. Write a Program in C to Swap the values of two variables without using any extra variable.

Output

x: 10 , y: 20 x: 20 , y: 10

5. Write a Program to Replace all 0’s with 1’s in a Number.

Output:

6. Write a Program to convert the binary number into a decimal number.

Output

7. Write a Program to check if the year is a leap year or not.

Output

2000 is a leap year. 2002 is not a leap year. 2008 is a leap year.

8. Write a program to Factorial of a Number.

Output

Factorial of 13 is 6227020800 Factorial of 9 using recursion:362880

9. Write a Program to Check if a number is an Armstrong number or not.

Output

False True

10. Write a program to Find all the roots of a quadratic equation in C.

Output:

Roots are real and different
15.937254
0.062746

11. Write a Program to reverse a number.

Output

Initial number:15942 24951 after reverse using iteration 15942 after again reverse using recursion

12. Check whether a number is a palindrome.

Output

13431 is palindrome 12345 is not a palindrome

13. Write a C Program to check if two numbers are equal without using the bitwise operator.

Output

1 is not equal to 2

14. Write a C program to find the GCD of two numbers.

Output

GCD of 98 and 56 is 14

15. Write a C program to find the LCM of two numbers.

Output

16. Write a C Program to find the Maximum and minimum of two numbers without using any loop or condition.

Output

max = 55 min = 23

17. Write a Program in C to Print all natural numbers up to N without using a semi-colon.

Output

1 2 3 4 5 6 7 8 9 10

18. Write a Program to find the area of a circle.

Output

Area is 78.550000

19. Write a Program to create a pyramid pattern using C.

Output

20. Write a program to form Pascal Triangle using numbers.

Output

1 1 1 1 2 1 1 3 3 1 1 4 6 4 1

21. Write a Program to return the nth row of Pascal’s triangle.

Output

1,5 ,10 ,10 ,5 ,1

22. Write a program to reverse an Array.

Output

5 4 3 2 1

23. Write a program to check the repeating elements in C.

Output

1 3 5

24. Write a Program to print the Maximum and Minimum elements in an array.

Output

Smallest: 2 and Largest: 83

25. Write a Program for the cyclic rotation of an array to k positions.

Output

3 4 5 1 2

26. Write a Program to sort First half in Ascending order and the Second in Descending order.

Output

11 16 23 83 73 59 42

27. Write a Program to print sums of all subsets in an array.

Output

6 3 4 1 5 2 3 0

28. Write a Program to Find if there is any subarray with a sum equal to 0.

Output

True subarray with 0 sum is possible

29. Write a C program to Implement Kadane’s Algorithm

Output

Maximum contiguous sum is 7 Starting index 2 Ending index 6

30. Write a Program to find the transpose of a matrix.

Output

Result matrix is 1 2 3 1 2 3 1 2 3 1 2 3

31. Write a Program to Rotate a matrix by 90 degrees in the clockwise direction in C.

Output

Orignal Matrix: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Matrix after rotation: 13 9 5 1 14 10 6 2 15 11 7 3 16 12 8 4

32. Write a Program to find the Spiral Traversal of a Matrix in C.

Output

1 5 9 13 14 15 16 12 8 4 3 2 6 10 11 7

33. Write a program to count the sum of numbers in a string.

Output

34. Program to calculate the length of the string.

Output

length using strlen:13 length using iteration:13 length using recursion:13

35. Write a program to check string is a palindrome.

Output

GeekeeG is a palindrome Checking GeeksforGeeks using recursive approach Not a Palindrome

36. Write a program to print all permutations of a given string in lexicographically sorted order in C.

Output

123 132 213 231 312 321

37. Write a program to calculate the Power of a Number using Recursion in C.

Output

38. Write a Code to print the Fibonacci series using recursion.

Output

Fibonacci using recursion of 9:34 Fibonacci using iteration of 11:144

39. Write a Program to find the HCF of two Numbers using Recursion.

Output

GCD of 192 and 36 is 12

40. Write a Program in C to reverse a string using recursion.

Output

Orignal string:Geeks for Geeks Reverse the string(iteration):skeeG rof skeeG Using recursion for reverse:Geeks for Geeks

41. Write a C Program to search elements in an array.

Output

Element is present at index 4

42. Write a C Program to search elements in an array using Binary Search.

Output

Element is present at index 4

43. Write a C Program to sort arrays using Bubble, Selection, and Insertion Sort.

Output

Non-Sorted array: 9 4 3 11 1 5 Sorted array using Bubble sort: 1 3 4 5 9 11 Non-Sorted array: 4 3 9 1 5 11 Sorted array using Insertion Sort: 1 3 4 5 9 11 Non-Sorted array: 5 1 11 3 4 9 Sorted array using Selection Sort: 1 3 4 5 9 11

44. Write a C Program to sort arrays using Merge Sort.

Output

Given array:23 9 13 15 6 7 Sorted array :6 7 9 13 15 23

45. Write a C Program to sort arrays using Quick Sort.

Output

Unsorted Array:28 7 20 1 10 3 6 Sorted array :1 3 6 7 10 20 28

46. Write a program to sort an array using pointers.

Output

4 7 12 13 22

47. Write a C program to Store Information about Students Using Structure

Output

Student Records: Name : Geeks1 Roll Number : 1 Age : 10 Name : Geeks2 Roll Number : 2 Age : 11 Name : Geeks3 Roll Number : 3 Age : 13

48. Write a C Program To Add Two Complex Numbers Using Structures And Functions.

Output

x = 4 + 5i y = 7 + 11i sum = 11 + 16i

49. Write a C Program to add Two Distance Given as Input in Feet and Inches

Output

Feet Sum: 31 Inch Sum: 5.70

50. Write a C program to reverse a linked list iteratively

Output

Given linked list 25 19 14 10 Reversed linked list 10 14 19 25

Conclusion

In this C coding interview questions and answers, we’ve compiled a wide-range of practice questions suitable for individuals at all levels, from beginners to advanced learners. Exploring these questions and their solutions will not only enhance your proficiency in C but also prepare you for a successful coding interview experience.

C Coding Interview Questions – FAQs

Q: What are the most common C coding interview questions?

C syntax and semantics
Data structures and algorithms
Memory management
Pointers
File I/O

Reverse a linked list.
Implement a binary search tree.
Write a function to find the maximum element in an array.
Explain the difference between a pointer and an array.
What is the difference between a function declaration and a function definition?
How do you allocate memory on the heap?
How do you free memory that has been allocated on the heap?
What is a dangling pointer?
How do you read and write data to a file?

Q. Who can benefit from these C coding interview questions and answers?

These questions are designed to benefit anyone preparing for a C coding interview. Whether you’re a beginner looking to learn the fundamentals or an experienced programmer aiming to enhance your C skills, this resource can assist you in your preparation.

Q: How can I use these questions effectively in my interview preparation?

Start by assessing your current level of expertise in C programming language. Then, you can use these questions to gradually build your skills up and knowledge. Practice solving them on your own, and review the explanations to ensure a thorough understanding.