In the past, numerous articles on frequently asked C Interview Questions had been posted. All those questions were accompanied with clear answers and supporting code examples wherever appropriate.

An ebook named “Favourite 50 – C Question Bank” had been created and posted to the downloads page of Interview Mantra. That ebook was a result of aggregation of all the C Interview questions and answers posted in Interview Mantra. That was the first edition of this ebook. The ebook was downloaded 8756 times till the date this post had been written.

Inspired by the success of first edition, we have come up with the second edition that includes few corrections, additions and major formatting changes. This book is available for free download exclusively for the readers of Interview Mantra.

Click here to download the second edition of the ebook “Favourite 50 – C Question Bank“

I discovered a great website that comprehensively covers puzzles and questions in C language.

Gowrikumar.com – C Puzzles

What’s special about these puzzles and questions is that some of these questions are asked in interviews of experienced C programmers at Multi National Companies. The standard of the questions and answers at the above site is pretty high, usually suits programmers with prior experience or expertise in C.

The man behind this website is CH. Gowri Kumar. He is from Hyderabad-India. He is a masters graduate from Indian Institute of science and has over 7 years of Software development experience with top IT companies such as HP, Motorola, Microsoft etc.

If you are a C lover, be sure to subscribe to the Google group, Programming Puzzles maintained by Gowrikumar himself. You can get all your C programming questions solved by the vibrant and active community there.

Comment below if you know sites similar to these which cover C programs.

This post has few of basic number pattern programs in C. Question.56(multiplication table) tests the ability to convert an elementary algorithm into a program. Question.57, Question.58 are programs that test the ability of candidate to use nested while/for loops to print special number patterns. Question.59, Question.60 test ability of using simple while/for loops and basics of formatting using printf statement. See all C interview questions in this blog in one page.

Also Read:

• Star Pattern Programs
• Number Pattern Programs

Showing 5 out of 65 C Interview Questions.

1. Write a program to display the multiplication table of a given number.

Program: Multiplication table of a given number

#include <stdio.h>
int main() {
      int num, i = 1;
      printf("\n Enter any Number:");
      scanf("%d", &num);
      printf("Multiplication table of %d: \n", num);
      while (i <= 10) {
            printf("\n %d x %d = %d", num, i, num * i);
            i++;
      }
      return 0;
}

Download Code

Output:

Enter any Number:5
 5 x 1 = 5
 5 x 2 = 10
 5 x 3 = 15
 5 x 4 = 20
 5 x 5 = 25
 5 x 6 = 30
 5 x 7 = 35
 5 x 8 = 40
 5 x 9 = 45
 5 x 10 = 50

Explanation: We need to multiply the given number (i.e. the number for which we want the multiplication table) with value of ‘i’ which increments from 1 to 10.

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2. Write C program to print the following pattern:

         1
        2 2
       3 3 3
      4 4 4 4
     5 5 5 5 5

Program:

#include<stdio.h>
int main() {
    int i, j, k, c = 5;
    for (i = 1; i <= 5; i++) {
            /* k is taken for spaces */
            for (k = 1; k <= c; k++) {
                  /* blank space */
                  printf(" ");
            }
            for (j = 1; j <= i; j++) {
                  /* %2d ensures that the number is printed in
two spaces for alignment and the numbers are printed in the order. */
                  printf("%2d", i);
            }
            printf("\n");
            /*c is decremented by 1 */
            c--;
      }
      return 0;
}

Download Code

Output:

         1
        2 2
       3 3 3
      4 4 4 4
     5 5 5 5 5

Explanation: Here ‘i’ loop is used for printing the numbers in the respective rows and ‘k’ loop is used for providing spaces. ‘j’ loop prints the numbers. ‘c’ is decremented for numbers to be displayed in alternate columns.

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3. Write C program to print the following pattern:

         1
       1 2 1
     1 2 3 2 1
   1 2 3 4 3 2 1
 1 2 3 4 5 4 3 2 1

Program:

#include<stdio.h>
int main() {
      /* c taken for columns */
      int i, j, c = 9, m, k;
      for (i = 1; i <= 5; i++) {
            /* k is used for spaces */
            for (k = 1; k <= c; k++) {
                  printf(" ");
            }
            for (j = 1; j <= i; j++) {                   printf("%2d", j);             }             for (m = j - 2; m > 0; m--) {
                  /* %2d ensures that the number
                   * is printed in two spaces
                   * for alignment */
                  printf("%2d", m);
            }
            printf("\n");
            /* c is decremented by 2 */
            c = c - 2;
      }
      return 0;
}

Download Code

Output:

         1
       1 2 1
     1 2 3 2 1
   1 2 3 4 3 2 1
 1 2 3 4 5 4 3 2 1

Explanation: Here ‘i’ loop is used for printing numbers in rows and ‘k’ loop is used for providing spaces. ‘j’ loop is used for printing numbers in increasing order. ‘m’ loop is used for printing numbers in reverse order.

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4. Write a C program to display the following format:

------
  a b
 ------
  1 5
  2 4
  3 3
  4 2
  5 1
 ------

Program:

#include<stdio.h>
int main() {
      int i = 1, j = 5;
      printf("----------\n");
      printf("a \t b \n");
      printf("----------\n");
      /* logic: while loop repeats
       * 5 times i.e. until
       * the condition i<=5 fails */
      while (i <= 5) {
            /* i and j value printed */
            printf("%d \t %d\n", i, j);
            /* i and j value incremented
             by 1 for every iteration */
            i++;
            j--;
      }
      printf("----------");
      return 0;
}

Download Code

Output:

------
  a b
 ------
  1 5
  2 4
  3 3
  4 2
  5 1
 ------

Explanation: Here, ‘i’ is initialized to least value 1 and ‘j’ initialized to highest value 5. We keep incrementing the i’ value and decrementing the ‘j’ value until the condition fails. The value is displayed at each increment and at each decrement. Back to top

5. Write a C program to display the following format:

--------
 no. sum
 --------
  1  1
  2  3
  3  6
  4  10
  5  15
 --------

Program:

#include<stdio.h>
int main() {
      int num = 1, sum = 0;
      printf("-----------\n");
      printf("num \t sum\n");
      printf("-----------\n");
      /* while loop repeats 5 times
       *  i.e. until the condition
       *  num <= 5 fails */
      while (num <= 5) {
            sum = sum + num;
            printf("%d \t %d\n", num, sum);
            /* num incremented by 1
             * for every time
             * the loop is executed */
            num++;
      }
      printf("-----------");
      return 0;
}

Download Code

Output:

--------
 no. sum
 --------
  1  1
  2  3
  3  6
  4  10
  5  15
 --------

Explanation: In the above program we have taken two variables ‘num’ and ‘sum’. ‘num’ is used to check the condition and to display the numbers up to 5. ‘sum’ is used to add the numbers which are displayed using variable ‘num’. The ‘sum’ value is initialized to zero. sum is added to the numbers which are incremented by ‘i’ and displayed.

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Also read 10 Challenging Pattern Programs

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