C Program to Convert Decimal to Octal Number

We have created a user defined function decimalToOctal() for decimal to octal conversion. The program takes the decimal number(entered by user) as input and converts it into an octal number using the function.

Program :

#include <stdio.h>
#include <math.h>
/* This function converts the decimal number "decimalnum"
 * to the equivalent octal number
 */
int decimalToOctal(int decimalnum)
{
    int octalnum = 0, temp = 1;

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

    return octalnum;
}
int main()
{
    int decimalnum;

    printf("Enter a Decimal Number: ");
    scanf("%d", &decimalnum);

    printf("Equivalent Octal Number: %d", decimalToOctal(decimalnum));

    return 0;
}

Output :

Enter a Decimal Number: 405
Equivalent Octal Number: 625