100 Interview Questions -

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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 

1. 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 

1. 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. 

1. 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 

1. 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 

1. 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:

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

1. 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. 

1. 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. 

1. 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 

1. 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 

2. 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. 

3. 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. 

4. 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. 

5. 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 

6. 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. 

7. 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 

8. 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. 

9. 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 

10. 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 

11. 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. 

12. 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. 

13. 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:
    

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

14. 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). 

15. 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. 

16. 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! 

17. 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. 

18. 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 

19. 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. 

20. 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. 

21. 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 

22. Question 31:
    Question: Create a C program that prints a right-angled triangle pattern of asterisks using nested for loops.
    Expected Output:
    

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

23. 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 ***** * * * * * * ***** 

24. Question 33:
    Question: Write a C program that prints a mirrored right-angled triangle pattern of numbers.
    Expected Output:
    

     1 12 123 1234 12345 

25. Question 34:
    Question: Create a program that prints a pyramid pattern of asterisks with a user-specified height.
    Expected Output:
    

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

26. 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 

27. 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 

28. 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 * ** * * * * ***** 

29. Question 38:
    Question: Develop a C program that prints an inverted pyramid pattern of numbers.
    Expected Output:
    

    12345 1234 123 12 1 

30. 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 

31. Question 40:
    Question: Create a C program that prints a pattern of the letter 'X' formed by asterisks.
    Expected Output:
    

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

32. 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. 

33. 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 ***** * * * * * * ***** 

34. 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. 

35. 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. 

36. 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. 

37. 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. 

38. 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. 

39. 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. 

40. 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. 

41. 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 

42. 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. 

43. 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. 

44. 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. 

45. 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. 

46. 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 

47. 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. 

48. 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:
    

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

49. 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. 

50. 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. 

51. 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. 

52. 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 

53. 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 

54. 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. 

55. 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. 

56. 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. 

57. 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. 

58. 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. 

59. 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. 

60. 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. 

61. 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. 

62. 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. 

63. 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. 

64. 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. 

65. 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. 

66. 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. 

67. 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. 

68. 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. 

69. 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. 

70. 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. 

71. 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. 

72. 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 

73. 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. 

74. 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. 

75. 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. 

76. 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. 

77. 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. 

78. 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. 

79. 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. 

80. 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. 

81. 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. 

82. 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 

83. 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 

84. 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 - - - - - ... 

85. 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". 

86. 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 * * * * * * * * # * # # # # # # # # # # # # # # # # # # # # # # # # # * # # # # # # # # # # 

87. 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 ... 

88. 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. 

89. 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. 

90. 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. 

91. 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