C Program to Convert a Decimal Number to Binary & Count the Number of 1s

This C Program converts a decimal number into binary & count the number of 1s. The program uses module operation and multiplication with base 2 operation for conversion. It also uses modulo operation to check for 1’s and accordingly increments the count of 1s.

Here is source code of the C program to convert a decimal number to binary & count the number of 1s. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

1. /*

2.  * C program to accept a decimal number and convert it to binary

3.  * and count the number of 1's in the binary number

4.  */

5. #include <stdio.h>

7. void main()

8. {

9.     long num, decimal_num, remainder, base = 1, binary = 0, no_of_1s = 0;

11.     printf("Enter a decimal integer \n");

12.     scanf("%ld", &num);

13.     decimal_num = num;

14.     while (num > 0)

15.     {

16.         remainder = num % 2;

17.         /*  To count no.of 1s */

18.         if (remainder == 1)

19.         {

20.             no_of_1s++;

21.         }

22.         binary = binary + remainder * base;

23.         num = num / 2;

24.         base = base * 10;

25.     }

26.     printf("Input number is = %d\n", decimal_num);

27.     printf("Its binary equivalent is = %ld\n", binary);

28.     printf("No.of 1's in the binary number is = %d\n", no_of_1s);

29. }

$ cc pgm46.c
$ a.out
Enter a decimal integer
134
Input number is = 134
Its binary equivalent is = 10000110
No.of 1's in the binary number is = 3