91+ Most Asked C Coding Questions In Interview

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🧑‍💻 By Prakash Kumar • 📝 Updated on: 14 May 2025

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This Page has a massive bunch of most commonly asked and most important tricky coding question in c for freshers to crack the coding interview rounds.

Along with the of pattern programming in C, in coding rounds, interviewers commonly gives you some question to write a program on it.

This Programs may contain some operations to perform on numbers, strings, arrays or on linked list. 

Below are the c programs asked in coding round which are categoried section wise. Prepare each variety of coding questions which is very important and will help you to crack your coding rounds.

Coding Question in C on Numbers

  1. Write a program to reverse an integer in C.
  2. Write a program in C to check whether an integer is Armstrong number or not.
  3. Write a program in C to check given number is prime or not.
  4. Write a program in C to print the Fibonacci series using iteration.
  5. Write a program in C to print the Fibonacci series using recursion.
  6. Write a program in C to check whether a number is palindrome or not using iteration.
  7. Write a program in C to check whether a number is palindrome or not using recursion.
  8. Write a program in C to find greatest among three integers.
  9. Write a program in C to check if a number is binary.
  10. Write a program in C to find sum of digits of a number using recursion.
  11. Write a program in C to swap two numbers without using third variable.
  12. Write a program in C to swap two numbers using third variable.
  13. Write a program in C to find prime factors of a given integer.
  14. Write a program in C to add two integer without using arithmetic + operator.
  15. Write a program in C to check given number is perfect or not.
  16. C Program to find the Average of numbers with explanations.
  17. C Program to calculate factorial using iterative method.
  18. C Program to calculate factorial using recursion.
  19. C Program to check a given number is even or odd.
  20. C program to print first n Prime Number with explanation.
  21. C Program to print Prime Number in a given range
  22. C Program to find Smallest number among three.
  23. C program to calculate the power using the POW method.
  24. C Program to calculate the power without using POW function.
  25. C Program to calculate the square of a given number.
  26. C Program to calculate the cube of a given number
  27. C Program to calculate the square root of a given number.
  28. C program to calculate LCM of given two numbers.
  29. C Program to find GCD or HCF of two numbers.
  30. C Program to find GCD of two numbers using recursion.
  31. C Program to Convert Decimal Number into Binary.
  32. C Program to convert Decimal number to Octal number.
  33. C Program to check the given year is a leap year or not.
  34. C Program to convert Celsius to Fahrenheit.
  35. C Program to convert Fahrenheit to Celsius.
  36. C program to calculate Simple Interest with explanation.

C Coding Interview Questions on String

  1. Write a method in C which will remove any given character from a String.
  2. Write a program in C to count occurrence of a given character in a String.
  3. Write a program in C to check if two Strings are Anagram.
  4. Write a program in C to check a String is palindrome or not.
  5. C program to check given character is vowel or consonant.
  6. C program to check given character is digit or not.
  7. C program to replace the string space with a given character.
  8. C program to convert lowercase char to uppercase of string.
  9. C program to convert lowercase vowel to uppercase in string.
  10. C program to delete vowels in a given string.
  11. C program to count Occurrence Of Vowels & Consonants in a String.
  12. C program to print the highest frequency character in a String.
  13. C program to Replace First Occurrence Of Vowel With ‘-‘ in String.
  14. C program to count alphabets, digits and special characters.
  15. C program to separate characters in a given string.
  16. C program to remove blank space from string.
  17. C program to remove blank space from string.
  18. C program to concatenate two strings.
  19. C program to remove repeated character from string.
  20. C program to calculate sum of integers in string.
  21. C program to print all non repeating character in string.
  22. C program to copy one string to another string.
  23. C Program to sort characters of string.
  24. C Program to sort character of string in descending order.

Coding Questions in C on Array

  1. Write a program in C for, In array 1-100 numbers are stored, one number is missing how do you find it.
  2. Write a program in C for, In a array 1-100 multiple numbers are duplicates, how do you find it.
  3. Write a program in C to find first duplicate number in a given array.
  4. Write a program in C to remove duplicate elements form array in C.
  5. Write a program in C for, Given two arrays 1,2,3,4,5 and 2,3,1,0,5 find which number is not present in the second array.
  6. Write a program in C for, How to compare two array is equal in size or not.
  7. Write a program in C to find largest and smallest number in array.
  8. Write a program in C to find second highest number in an integer array.
  9. Write a program in C to find top two maximum number in array?
  10. C program to print array in reverse Order.
  11. C program to reverse an Array in two ways.
  12. C Program to calculate length of an array.
  13. C program to insert an element at end of an Array.
  14. C program to insert element at a given location in Array.
  15. C Program to delete element at end of Array.
  16. C Program to delete given element from Array.
  17. C Program to delete element from array at given index.
  18. C Program to find sum of array elements.
  19. C Program to print all even numbers in array.
  20. C Program to print all odd numbers in array.
  21. C program to perform left rotation of array elements by two positions.
  22. C program to perform right rotation in array by 2 positions.
  23. C Program to merge two arrays.
  24. C Program to find highest frequency element in array.
  25. C Program to add two number using recursion.
  26. C Program to find sum of digit of number using recursion.

C Coding Interview Questions on Linked List

  1. Write a program in C to reverse a singly linked list.
  2. Write a program in C to find 3rd element of Linked List from last in single pass.
  3. Write a program in C to find middle element of a linked list in single pass.
  4. Write a Program in C to Insert a node at the beginning, at End and at given location of the Singly linked list.
  5. Write a Program in C to Search an element of the Singly linked list.
  6. Write a Program in C to Delete a node at the beginning, at end and at given location of the Singly linked list.
  7. Write a Program in C to Reverses the Singly linked list.

C Interview Questions on Searching and Sorting

  1. Write a program in C to implement Insertion Sort.
  2. Write a program in C to implement Bubble Sort.
  3. Write a program in C to implement Selection Sort.
  4. Write a program in C to implement Quick Sort.
  5. Write a program in C to implement Heap Sort.
  6. Write a program in C to implement Radix Sort.

Binary Tree Coding question in C

Coming Soon (Work is in progress for this section)

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