https://github.com/pankaj-str/c-interview-questions
C Programs: Practicing and solving problems is the best way to learn anything
https://github.com/pankaj-str/c-interview-questions
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C Programs: Practicing and solving problems is the best way to learn anything
- Host: GitHub
- URL: https://github.com/pankaj-str/c-interview-questions
- Owner: Pankaj-Str
- Created: 2023-05-17T09:28:22.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2023-10-12T15:40:46.000Z (over 2 years ago)
- Last Synced: 2025-04-12T00:53:11.965Z (about 1 year ago)
- Topics: c, cprogramming, cprogramming-language, cquestions, interview-questions
- Homepage:
- Size: 85 KB
- Stars: 28
- Watchers: 2
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
# 100 Interview Questions -
1. **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
```
2. **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
```
3. **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.
```
4. **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
```
5. **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
```
6. **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:**
```
*
**
***
****
*****
```
7. **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.
```
8. **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.
```
9. **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
```
10. **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
```
11. **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.
```
12. **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.
```
13. **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.
```
14. **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
```
15. **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.
```
16. **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
```
17. **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.
```
18. **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
```
19. **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
```
20. **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.
```
21. **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.
```
22. **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:**
```
*
***
*****
*******
*****
***
*
```
23. **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).
```
24. **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.
```
25. **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!
```
26. **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.
```
27. **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
```
28. **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.
```
29. **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.
```
30. **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
```
31. **Question 31:**
**Question:** Create a C program that prints a right-angled triangle pattern of asterisks using nested `for` loops.
**Expected Output:**
```
*
**
***
****
*****
```
32. **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
*****
* *
* *
* *
*****
```
33. **Question 33:**
**Question:** Write a C program that prints a mirrored right-angled triangle pattern of numbers.
**Expected Output:**
```
1
12
123
1234
12345
```
34. **Question 34:**
**Question:** Create a program that prints a pyramid pattern of asterisks with a user-specified height.
**Expected Output:**
```
*
***
*****
*******
*********
```
35. **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
```
36. **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
```
37. **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
*
**
* *
* *
*****
```
38. **Question 38:**
**Question:** Develop a C program that prints an inverted pyramid pattern of numbers.
**Expected Output:**
```
12345
1234
123
12
1
```
39. **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
```
40. **Question 40:**
**Question:** Create a C program that prints a pattern of the letter 'X' formed by asterisks.
**Expected Output:**
```
* *
* *
* *
* *
*
* *
* *
* *
* *
```
41. **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.
```
42. **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
*****
* *
* *
* *
*****
```
43. **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.
```
44. **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.
```
45. **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.
```
46. **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.
```
47. **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.
```
48. **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.
```
49. **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.
```
50. **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
```
51. **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.
```
52. **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.
```
53. **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.
```
54. **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.
```
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
```
56. **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.
```
57. **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:**
```
*
**
***
****
*****
```
58. **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.
```
59. **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.
```
60. **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.
```
61. **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
```
62. **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
```
63. **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.
```
64. **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.
```
65. **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.
```
66. **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.
```
67. **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.
```
68. **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.
```
69. **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.
```
70. **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.
```
71. **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.
```
72. **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.
```
73. **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.
```
74. **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.
```
75. **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.
```
76. **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.
```
77. **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.
```
78. **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.
```
79. **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.
```
80. **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.
```
81. **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
```
82. **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.
```
83. **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.
```
84. **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.
```
85. **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.
```
86. **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.
```
87. **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.
```
88. **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.
```
89. **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.
```
90. **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.
```
91. **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
```
92. **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
```
93. **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 - -
- - -
...
```
94. **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".
```
95. **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 * * * * * * *
* # * #
# # # # # # # #
# # # # #
# # # # # # # #
# # # *
# # # # # # # # # #
```
96. **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
...
```
97. **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.
```
98. **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.
```
99. **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.
```
100. **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
```