Program to Convert Octal Number to Binary Number in c++

#include<iostream>
#include<conio.h>
#include<math.h>
using namespace std;
int Octal_to_Binary(long n)
{
        long binary_num = 0, decimal_num = 0, i = 0;
        while(n!=0)
        {
                decimal_num = decimal_num + ((n%10) * pow(8,i));
                ++i;
                n = n/10;
        }
        i = 1;
        while(decimal_num!=0)
        {
                binary_num = binary_num + ((decimal_num % 2) * i);
                decimal_num = decimal_num/2;
                i = i*10;
        }
        return binary_num;
}
int main()
{
        long num;
        cout<<"Enter a octal number : ";
        cin>>num;
        cout<<"Octal Number "<<num<<" is equal to "<<Octal_to_Binary(num)<<" Binary Number."<<endl;
        getch();
        return 0;
}


Output