binary to decimal in cpp

 // Online C++ compiler to run C++ program online

#include <iostream>

#include <math.h>

using namespace std;

int main() {

    int a;

    cout<<"Enter the number";

    cin>>a;

    int answer = 0;

    int i =0;

    while(a!=0){

      int bit = a % 10;

      if(bit == 1){

         answer = pow(2,i) + answer;

      }

      a = a/10;

      i++;

    }

     cout<<answer;

    return 0;

}