string to number in c 2b 2b

1#include <iostream>
2#include <string>
3
4int main() {
5
6    std::string str = "123";
7    int num;
8
9    // using stoi() to store the value of str1 to x
10    num = std::stoi(str);
11
12    std::cout << num;
13
14    return 0;
15}

1int thing = std::stoi(string);

1// For C++11 and later versions
2string str1 = "45"; 
3string str2 = "3.14159"; 
4string str3 = "31337 geek"; 
5
6int myint1 = stoi(str1); 
7int myint2 = stoi(str2); 
8int myint3 = stoi(str3); 
9
10// Output
11stoi("45") is 45
12stoi("3.14159") is 3
13stoi("31337 geek") is 31337 

1atoi( str.c_str() )

1#include<string>
2string str1 = "45"; 
3string str2 = "3.14159"; 
4string str3 = "31337 geek";
5
6int myint1 = stoi(str1);
7std::cout<<stoi(str1);

1#include <iostream>
2#include <sstream>
3using namespace std;
4int main()
5{
6	string str = "123456";
7 	int n;
8  	stringstream ( str ) >> n;
9	cout << n; //Output:123456
10	return 0;
11}