Binary to decimal

#include <stdio.h>

int main(){

    long
        num,
        decimal_val = 0,
        base = 1,
        rem;

    scanf("%ld", &num);

    while (num > 0){

        rem = num % 10;
        decimal_val = decimal_val + rem * base;
        num = num / 10 ;
        base = base * 2;
    }
    printf("%ld", decimal_val);

    return 0;
}