Answers for "fastest wa to convert string to integer c++"

how to string to integer in c++

#include<string>
string str1 = "45"; 
string str2 = "3.14159"; 
string str3 = "31337 geek";

int myint1 = stoi(str1);
std::cout<<stoi(str1);

how to convert string to int in c++

string s = "123";
int n = s.size();
int num = 0;
 for(int i = 0 ; i<n;i++)//this what stoi built function do XD
 {
  num = num*10+(s[i]-'0');
 }