best way to convert string to a mnumber c++ code example

Example 1: convert stirng to int c++

int thing = std::stoi(string);

Example 2: convert string to number c++

#include <iostream>
#include <sstream>
using namespace std;
int main()
{
	string str = "123456";
 	int n;
  	stringstream ( str ) >> n;
	cout << n; //Output:123456
	return 0;
}