Convert Octal to Binary in C

In this source code example, we will write a code to convert the Octal to a binary number in the C programming language.

Convert Octal to Binary in C

In this C program, we will take input from the User or console and print the result to the output: 

#include <math.h>
#include <stdio.h>

long octalToBinary(int octalnum)
{
    int decimalnum = 0, i = 0;
    long binarynum = 0;

    while (octalnum != 0)
    {
        decimalnum = decimalnum + (octalnum % 10) * pow(8, i);
        i++;
        octalnum = octalnum / 10;
    }

    i = 1;
    while (decimalnum != 0)
    {
        binarynum = binarynum + (long)(decimalnum % 2) * i;
        decimalnum = decimalnum / 2;
        i = i * 10;
    }

    return binarynum;
}

int main()
{
    int octalnum;

    printf("Enter an octal number: ");
    scanf("%d", &octalnum);

    // Calling the function octaltoBinary
    printf("Equivalent binary number is: %d", octalToBinary(octalnum));
    return 0;
}

Output:

Enter an octal number: 12
Equivalent binary number is: 1010

Demo

Convert Octal to Binary in C