C program to convert Binary to Octal number system

Method 1

#include <stdio.h>
 
int main()
 
{
 
    int octalConstant[] = {0, 1, 10, 11, 100, 101, 110, 111};
 
    long long binary, octal, tempBinary;
 
    int digit, place, i;
 
    octal = 0;
 
    place= 1;
     
    /* Input binary number from user */
 
    printf("Enter any binary number: ");
 
    scanf("%lld", &binary);
 
    /* Copy original binary value to temp variable */
 
    tempBinary = binary;
     
    while(tempBinary != 0)
    {
     
        /* Extract last three digit of binary */
     
        digit = tempBinary % 1000;
 
        /* Find octal equivalent of 3 digit binary */
     
        for(i=0; i<8; i++)
     
        {
     
            if(octalConstant[i] == digit)
     
            {
                /*
                 * Increase the place value of octal
                 * and add the previous octal value
                 */
     
                octal = (i * place) + octal;
     
                break;
            }
        }
 
        /* Remove the last three digit of binary */
     
        tempBinary /= 1000;
 
        /* Increase the place value */
     
        place *= 10; 
    }
 
    printf("Original binary number = %lld\n", binary);
     
    printf("Octal number = %lld", octal);
 
    return 0;
}

Output

Enter any binary number: 11001111
Original binary number = 11001111
Octal number = 317