Codes With Pankaj

Posted on Oct 18, 2023

100 Interview Questions C

#cprogramming #interviewquestion

100 Interview Questions -

Question 1: Question: Write a C program that prints numbers from 1 to 10 using a for loop. Expected Output:

   1 2 3 4 5 6 7 8 9 10

Question 2: Question: Create a C program that prints the even numbers from 2 to 20 using a while loop. Expected Output:

   2 4 6 8 10 12 14 16 18 20

Question 3: Question: Develop a program that calculates the sum of numbers from 1 to 100 using a for loop. Expected Output:

   The sum of numbers from 1 to 100 is 5050.

Question 4: Question: Write a C program that prints the first 10 terms of the Fibonacci sequence using a do-while loop. Expected Output:

   Fibonacci series: 0 1 1 2 3 5 8 13 21 34

Question 5: Question: Create a program that prompts the user to enter a positive integer and then prints the multiplication table for that number from 1 to 10 using a for loop. Expected Output:

   Enter a number: 7
   Multiplication table for 7:
   7 x 1 = 7
   7 x 2 = 14
   ...
   7 x 10 = 70

Question 6: Question: Develop a C program that prints a pattern of asterisks in the shape of a right-angled triangle using nested for loops. Expected Output:

   *
   **
   ***
   ****
   *****

Question 7: Question: Write a program that calculates the factorial of a user-entered number using a while loop. Expected Output:

   Enter a number: 5
   The factorial of 5 is 120.

Question 8: Question: Create a C program that checks if a user-entered number is a prime number using a for loop. Expected Output:

   Enter a number: 17
   17 is a prime number.

Question 9: Question: Develop a program that finds and displays the prime numbers in a given range (e.g., 1 to 100) using a for loop. Expected Output:

   Prime numbers in the range 1 to 100 are: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Question 10:
Question: Write a C program that prints the ASCII values and characters for all printable characters (from ' ' to '~') using a for loop.
Expected Output:
```
ASCII values and characters for printable characters:
' ' (Space) - ASCII: 32
'!' - ASCII: 33
'"' - ASCII: 34
...
'~' - ASCII: 126
```
Question 11:
Question: Create a C program that calculates the sum of all even numbers between 1 and 50 using a for loop.
Expected Output:
```
The sum of even numbers from 1 to 50 is 650.
```
Question 12:
Question: Write a C program that checks if a user-entered number is a perfect number. A perfect number is a positive integer that is equal to the sum of its proper divisors (excluding itself).
Expected Output:
```
Enter a number: 28
28 is a perfect number.
```
Question 13:
Question: Develop a program that calculates the factorial of a user-entered number using a do-while loop.
Expected Output:
```
Enter a number: 6
The factorial of 6 is 720.
```
Question 14:
Question: Create a C program that prints the squares of numbers from 1 to 10 using a for loop.
Expected Output:
```
1^2 = 1
2^2 = 4
3^2 = 9
...
10^2 = 100
```
Question 15:
Question: Write a C program that calculates the sum of a geometric series (1 + 2 + 4 + 8 + ... + 2^n) using a for loop. Prompt the user for the number of terms (n).
Expected Output:
```
Enter the number of terms (n): 5
The sum of the geometric series is 31.
```
Question 16:
Question: Develop a C program that prints the first n terms of the square root series (1, sqrt(2), sqrt(3), ...) using a for loop.
Expected Output:
```
Enter the number of terms (n): 4
Square root series: 1.000 1.414 1.732 2.000
```
Question 17:
Question: Create a program that calculates the sum of an arithmetic series (3 + 7 + 11 + ... + 3n - 1) using a for loop. Prompt the user for the number of terms (n).
Expected Output:
```
Enter the number of terms (n): 5
The sum of the arithmetic series is 75.
```
Question 18:
Question: Write a C program that prints the numbers from 100 to 1 in reverse order using a while loop.
Expected Output:
```
100 99 98 97 96 ... 4 3 2 1
```
Question 19:
Question: Develop a program that generates and displays the Collatz sequence starting from a user-entered number. The Collatz sequence for a positive integer n is defined as follows: if n is even, divide it by 2; if n is odd, multiply it by 3 and add 1.
Expected Output:
```
Enter a number: 10
Collatz sequence: 10 5 16 8 4 2 1
```
Question 20:
Question: Create a C program that calculates and displays the GCD (greatest common divisor) of two user-entered numbers using the Euclidean algorithm in a while loop.
Expected Output:
```
Enter the first number: 24
Enter the second number: 18
The GCD of 24 and 18 is 6.
```
Question 21:
Question: Write a C program to check if a user-entered number is a palindrome. A palindrome is a number that reads the same forwards and backwards.
Expected Output:
```
Enter a number: 121
121 is a palindrome.
```
Question 22:
Question: Create a C program that prints a pattern of stars in the shape of a diamond using nested for loops.
Expected Output:
```
   *
  ***
 *****
*******
 *****
  ***
   *
```
Question 23:
Question: Develop a program that generates and displays a random number between 1 and 100. Prompt the user to guess the number, and provide hints.
Expected Output:
```
Guess the number (1-100): 50
Try higher.
Guess the number (1-100): 75
Try lower.
Guess the number (1-100): 63
Congratulations! You guessed the number (63).
```
Question 24:
Question: Write a C program that calculates the sum of the series 1 - 1/2 + 1/3 - 1/4 + ... - 1/n for a user-entered positive integer n.
Expected Output:
```
Enter a positive integer (n): 5
The sum of the series is -0.78333.
```
Question 25:
Question: Create a C program that simulates a simple game of rock-paper-scissors. The user plays against the computer.
Expected Output:
```
Choose your move (rock, paper, scissors): rock
Computer's move: scissors
You win!
```
Question 26:
Question: Develop a program that calculates the value of π using the Leibniz formula. Prompt the user for the number of terms (n) to use in the formula.
Expected Output:
```
Enter the number of terms (n): 1000000
The value of π is approximately 3.14159.
```
Question 27:
Question: Write a C program that generates a random password of a specified length (e.g., 8 characters) containing a mix of letters (both uppercase and lowercase) and numbers.
Expected Output:
```
Your random password: K4rW8p7X
```
Question 28:
Question: Create a C program that simulates a simple guessing game. The program generates a random number between 1 and 100, and the user must guess it within a limited number of attempts.
Expected Output:
```
Guess the number (1-100). You have 5 attempts.
Attempt 1: 50
Try higher.
Attempt 2: 75
Try lower.
...
Congratulations! You guessed the number (63) in 4 attempts.
```
Question 29:
Question: Develop a program that calculates the sum of all prime numbers between 1 and 100 using a for loop.
Expected Output:
```
The sum of prime numbers between 1 and 100 is 1060.
```
Question 30:
Question: Write a C program that generates and displays a magic square of order 3. A magic square is a square matrix in which the sum of the numbers in each row, column, and both main diagonals is the same.
Expected Output:
```
Magic Square:
2 7 6
9 5 1
4 3 8
```
Question 31:
Question: Create a C program that prints a right-angled triangle pattern of asterisks using nested for loops.
Expected Output:
```
*
**
***
****
*****
```
Question 32:
Question: Develop a program that prints a hollow square pattern of asterisks with a user-specified side length.
Expected Output:
```
Enter the side length of the square: 5
*****
*   *
*   *
*   *
*****
```
Question 33:
Question: Write a C program that prints a mirrored right-angled triangle pattern of numbers.
Expected Output:
```
    1
   12
  123
 1234
12345
```
Question 34:
Question: Create a program that prints a pyramid pattern of asterisks with a user-specified height.
Expected Output:
```
    *
   ***
  *****
 *******
*********
```
Question 35:
Question: Develop a C program that prints a diamond pattern of numbers with a user-specified number of rows.
Expected Output:
```
    1
   121
  12321
 1234321
123454321
 1234321
  12321
   121
    1
```
Question 36:
Question: Write a C program that prints a right-angled triangle pattern of uppercase letters starting from 'A'.
Expected Output:
```
A
AB
ABC
ABCD
ABCDE
```
Question 37:
Question: Create a program that prints a hollow right-angled triangle pattern of asterisks with a user-specified height.
Expected Output:
```
Enter the height of the triangle: 5
*
**
* *
*  *
*****
```
Question 38:
Question: Develop a C program that prints an inverted pyramid pattern of numbers.
Expected Output:
```
12345
 1234
  123
   12
    1
```
Question 39:
Question: Write a program that prints a square pattern of numbers with each row starting from 1 and incrementing by 1.
Expected Output:
```
12345
12345
12345
12345
12345
```
Question 40:
Question: Create a C program that prints a pattern of the letter 'X' formed by asterisks.
Expected Output:
```
*       *
 *     *
  *   *
   * *
    *
   * *
  *   *
 *     *
*       *
```
Question 41:
Question: Write a C program to calculate the sum of the first 10 natural numbers using a while loop.
Expected Output:
```
The sum of the first 10 natural numbers is 55.
```
Question 42:
Question: Create a C program that prints a hollow square pattern of asterisks with a user-specified side length.
Expected Output:
```
Enter the side length of the square: 5
*****
*   *
*   *
*   *
*****
```
Question 43:
Question: Write a C program that checks if a given number is a power of two (2^n).
Expected Output:
```
Enter a number: 16
16 is a power of 2.
```
Question 44:
Question: Create a C program to find the factorial of a user-entered number using a while loop.
Expected Output:
```
Enter a number: 5
The factorial of 5 is 120.
```
Question 45:
Question: Develop a program that calculates the sum of all odd numbers from 1 to 100 using a for loop.
Expected Output:
```
The sum of odd numbers from 1 to 100 is 2500.
```
Question 46:
Question: Write a C program that calculates the sum of the digits of a user-entered integer.
Expected Output:
```
Enter an integer: 12345
The sum of the digits is 15.
```
Question 47:
Question: Create a program that calculates the LCM (Least Common Multiple) of two user-entered numbers.
Expected Output:
```
Enter two numbers (separated by a space): 12 18
The LCM of 12 and 18 is 36.
```
Question 48:
Question: Develop a C program that checks if a user-entered string is a palindrome (reads the same forwards and backwards).
Expected Output:
```
Enter a string: radar
"radar" is a palindrome.
```
Question 49:
Question: Write a C program that calculates the sum of all the multiples of 3 and 5 between 1 and 100.
Expected Output:
```
The sum of multiples of 3 and 5 between 1 and 100 is 2418.
```
Question 50:
Question: Create a program that finds and displays the first N prime numbers.
Expected Output:
```
Enter the value of N: 10
The first 10 prime numbers are: 2 3 5 7 11 13 17 19 23 29
```
Question 51:
Question: Develop a program that checks if a user-entered year is a leap year using a logical operator.
Expected Output:
```
Enter a year: 2024
2024 is a leap year.
```
Question 52:
Question: Write a C program that calculates and displays the GCD (greatest common divisor) of two user-entered numbers.
Expected Output:
```
Enter two numbers (separated by a space): 24 18
The GCD of 24 and 18 is 6.
```
Question 53:
Question: Create a program that calculates the sum of squares of the first N natural numbers.
Expected Output:
```
Enter the value of N: 4
The sum of squares of the first 4 natural numbers is 30.
```

Question 54:
Question: Develop a program that finds the smallest and largest elements in an array of integers.
Expected Output:

Enter the number of elements in the array: 6
Enter the elements (separated by spaces): 18 7 42 10 31 55
The smallest element in the array is 7, and the largest element is 55.

Question 55:
Question: Write a C program that generates and displays a random password of a specified length (e.g., 8 characters) using a logical approach.
Expected Output:
```
Your random password: K4rW8p7X
```
Question 56:
Question: Create a program that checks if a user-entered number is a perfect number.
Expected Output:
```
Enter a number: 28
28 is a perfect number.
```
Question 57:
Question: Develop a C program that prints a pattern of stars in the shape of a right-angled triangle using nested for loops.
Expected Output:
```
*
**
***
****
*****
```
Question 58:
Question: Write a program that calculates the sum of even numbers between 1 and 50 using a while loop.
Expected Output:
```
The sum of even numbers from 1 to 50 is 650.
```
Question 59:
Question: Create a C program that checks if a given number is a palindrome using a logical approach.
Expected Output:
```
Enter a number: 121
121 is a palindrome.
```
Question 60:
Question: Write a C program that checks if a user-entered string is a palindrome using logical operations.
Expected Output:
```
Enter a string: radar
"radar" is a palindrome.
```
Question 61:
Question: Develop a C program that finds and displays the first N Fibonacci numbers.
Expected Output:
```
Enter the value of N: 8
The first 8 Fibonacci numbers are: 0 1 1 2 3 5 8 13
```
Question 62:
Question: Write a C program to reverse a user-entered string without using any built-in string functions.
Expected Output:
```
Enter a string: programming
Reversed string: gnimmargorp
```
Question 63:
Question: Create a program that checks if a given year is a leap year or not using a logical approach.
Expected Output:
```
Enter a year: 2100
2100 is not a leap year.
```
Question 64:
Question: Develop a C program that calculates the product of digits in a user-entered integer.
Expected Output:
```
Enter an integer: 12345
The product of the digits is 120.
```
Question 65:
Question: Write a program that determines if a user-entered number is prime or composite.
Expected Output:
```
Enter a number: 17
17 is a prime number.
```
Question 66:
Question: Create a C program that counts and displays the number of words in a user-entered sentence.
Expected Output:
```
Enter a sentence: This is a sample sentence.
The number of words in the sentence is 5.
```
Question 67:
Question: Develop a program that calculates the sum of all natural numbers divisible by 3 or 5 between 1 and 100.
Expected Output:
```
The sum of natural numbers divisible by 3 or 5 between 1 and 100 is 2418.
```
Question 68:
Question: Write a C program to check if a user-entered number is an Armstrong number (narcissistic number).
Expected Output:
```
Enter a number: 153
153 is an Armstrong number.
```
Question 69:
Question: Create a program that calculates the area of a triangle when the user provides the lengths of its three sides.
Expected Output:
```
Enter the lengths of three sides (separated by spaces): 5 12 13
The area of the triangle is 30 square units.
```
Question 70:
Question: Develop a C program to check if a user-entered number is a strong number.
Expected Output:
```
Enter a number: 145
145 is a strong number.
```
Question 71:
Question: Write a C program that checks if a user-entered number is a palindrome using a logical approach.
Expected Output:
```
Enter a number: 121
121 is a palindrome.
```
Question 72:
Question: Create a program that calculates the sum of squares of the first N even natural numbers.
Expected Output:
```
Enter the value of N: 4
The sum of squares of the first 4 even natural numbers is 120.
```
Question 73:
Question: Develop a C program that checks if a user-entered year is a leap year without using logical operators.
Expected Output:
```
Enter a year: 2024
2024 is a leap year.
```
Question 74:
Question: Write a program that calculates the sum of cubes of the first N odd natural numbers.
Expected Output:
```
Enter the value of N: 5
The sum of cubes of the first 5 odd natural numbers is 135.
```
Question 75:
Question: Create a C program that checks if a user-entered string is a pangram (contains all English alphabet letters).
Expected Output:
```
Enter a string: The quick brown fox jumps over the lazy dog.
The string is a pangram.
```
Question 76:
Question: Develop a program that calculates and displays the HCF (Highest Common Factor) of two user-entered numbers.
Expected Output:
```
Enter two numbers (separated by a space): 24 36
The HCF of 24 and 36 is 12.
```
Question 77:
Question: Write a C program that calculates the sum of the squares of prime numbers between 1 and 50.
Expected Output:
```
The sum of squares of prime numbers between 1 and 50 is 2418.
```
Question 78:
Question: Create a program that checks if a user-entered number is an abundant number.
Expected Output:
```
Enter a number: 12
12 is an abundant number.
```
Question 79:
Question: Develop a C program that checks if a given string is a palindrome using pointers.
Expected Output:
```
Enter a string: racecar
"racecar" is a palindrome.
```
Question 80:
Question: Write a program that calculates the sum of digits of a user-entered number using a logical approach.
Expected Output:
```
Enter a number: 12345
The sum of the digits is 15.
```
Question 81:
Question: Create a C program to find and display the prime factors of a user-entered number.
Expected Output:
```
Enter a number: 60
The prime factors of 60 are: 2 3 5
```
Question 82:
Question: Develop a program that calculates the difference between the sum of squares and the square of the sum of the first N natural numbers.
Expected Output:
```
Enter the value of N: 5
The difference is 170.
```
Question 83:
Question: Write a C program that checks if a user-entered number is a strong number using logical operations.
Expected Output:
```
Enter a number: 145
145 is a strong number.
```
Question 84:
Question: Create a program that calculates and displays the LCM (Least Common Multiple) of three user-entered numbers.
Expected Output:
```
Enter three numbers (separated by spaces): 12 18 24
The LCM of 12, 18, and 24 is 72.
```
Question 85:
Question: Develop a C program that calculates the sum of natural numbers divisible by both 3 and 5 between 1 and 100.
Expected Output:
```
The sum of natural numbers divisible by both 3 and 5 between 1 and 100 is 315.
```
Question 86:
Question: Write a program that checks if a user-entered number is a Kaprekar number.
Expected Output:
```
Enter a number: 9
9 is a Kaprekar number.
```
Question 87:
Question: Create a C program to find the sum of the series: 1 + 1/4 + 1/9 + 1/16 + ... + 1/n^2.
Expected Output:
```
Enter the value of n: 4
The sum of the series is approximately 1.42361.
```
Question 88:
Question: Develop a program that checks if a user-entered sentence is a palindrome (ignoring spaces and case).
Expected Output:
```
Enter a sentence: A man, a plan, a canal, Panama.
The sentence is a palindrome.
```
Question 89:
Question: Write a C program that calculates and displays the difference between the sum of even-indexed elements and odd-indexed elements in an array.
Expected Output:
```
Enter the number of elements in the array: 5
Enter the elements (separated by spaces): 4 7 2 9 6
The difference is 7.
```
Question 90:
Question: Create a program that calculates the value of π using the Monte Carlo method for a user-specified number of iterations.
Expected Output:
```
Enter the number of iterations: 1000000
The value of π is approximately 3.14159.
```
Question 91:
Question: Write a C program that generates the first N prime numbers and displays them in a spiral pattern.
Expected Output:
```
Enter the value of N: 10
Prime Numbers in a Spiral:
17 16 15 14 13
18  5  4  3 12
19  6  1  2 11
20  7  8  9 10
21 22 23 24 25
```

Question 92:
Question: Create a program that simulates a basic ATM machine. The user can withdraw, deposit, or check the balance.
Expected Output: (Interaction example)

Welcome to the ATM!
Select an option:
1. Withdraw
2. Deposit
3. Check Balance
4. Exit
Enter your choice: 1
Enter the amount to withdraw: 100
Successfully withdrawn $100. Current balance: $900

Question 93:
Question: Develop a C program that simulates a simple tic-tac-toe game for two players.
Expected Output: (Sample game interaction)

Player 1, enter your move (row and column): 2 1
Board after move:
1 - -
X - -
- - -
Player 2, enter your move (row and column): 1 2
Board after move:
1 O -
X - -
- - -
...

Question 94:
Question: Write a C program to find and display the longest word in a user-entered sentence.
Expected Output:
```
Enter a sentence: The quick brown fox jumps over the lazy dog.
The longest word in the sentence is "jumps".
```

Question 95:
Question: Create a program that generates a random maze and finds a path from the start to the end point.
Expected Output:

Random Maze:
# # # # # # # # # # #
S       #   #       #
# # #   # # #   # # #
#   #   #       #   #
#   # # #   # # # # #
#   #           #   E
# # # # # # # # # # #
Path:
S   * * * * * *   *
    *       #   * #
# # #   # # #   # #
#   #   #       # #
#   # # #   # # # #
#   #           # *
# # # # # # # # # #

Question 96:
Question: Develop a C program that simulates a simple Blackjack card game between the user and the computer.
Expected Output: (Sample game interaction)
```
Welcome to Blackjack!
Player's Hand: 7 9
Computer's Hand: 5 ?
Do you want to hit or stand? (h/s): h
Player's Hand: 7 9 Q
...
```
Question 97:
Question: Write a program to calculate the sum of prime numbers in the Fibonacci sequence up to a user-entered limit.
Expected Output:
```
Enter the limit: 50
The sum of prime Fibonacci numbers up to 50 is 104.
```

Question 98:
Question: Create a C program that counts the number of occurrences of each word in a user-entered text document.
Expected Output: (Sample input and output)

Enter the text:
This is a sample text. This is a sample document.
Word Count:
"This" occurs 2 times.
"is" occurs 2 times.
"a" occurs 2 times.
"sample" occurs 2 times.
"text." occurs 1 time.
"document." occurs 1 time.

Question 99:
Question: Develop a program that calculates and displays the sum of digits of factorial of a user-entered number.
Expected Output:
```
Enter a number: 5
The sum of digits of 5! is 3.
```
Question 100:
Question: Write a C program that generates and displays the first N numbers of the Lucas sequence.
Expected Output:
```
Enter the value of N: 8
The first 8 Lucas numbers are: 2 1 3 4 7 11 18 29
```

DEV Community

100 Interview Questions C

100 Interview Questions -

Top comments (0)

Read next

Tests with time

Front-End to Full-Stack Journey: SQL & SQLite

How to create efficient containers

Unit tests so you don't lose your levitating plant