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.

/*

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

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

 */

#include <stdio.h>

void main()

{

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

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

    scanf("%ld", &num);

    decimal_num = num;

    while (num > 0)

    {

        remainder = num % 2;

        /*  To count no.of 1s */

        if (remainder == 1)

        {

            no_of_1s++;

        }

        binary = binary + remainder * base;

        num = num / 2;

        base = base * 10;

    }

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

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

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

}

Output:

Enter a decimal integer

134

Input number is = 134

Its binary equivalent is = 10000110

No.of 1's in the binary number is = 3

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