Convert Octal Number to Decimal Number in c++

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


Output