C++二进制数转换十进制

/*
 * @Author: DEFT:errornotfound@qq.com  V:NOTFOUND6O6 
 * @Date: 2023-03-02 22:08:22
 * @LastEditors: Please set LastEditors
 * @LastEditTime: 2023-03-03 12:01:42
 * @FilePath: \WenkaiC\bin_to_dec.cpp
 * @Description: 
 * 
 * Copyright (c) 2023 by 1zPeasy, All Rights Reserved. 
 */
#include <iostream>
#include<math.h>
using namespace std;

int main(){
	string s;
	cin>>s;	//10110
	int sum=0;
	int weight = 2;
	// i = 0; i < 5;
	for(int i = 0; i<s.size();i++){
		int a = 0;
		a=(s.at(i)-'0') * pow(weight,(s.size()-i-1));
		sum = sum + a;
		
	}
	cout<< sum << endl;
	return 0;
}