for each loop sor string in cpp code example

Example 1: how to iterate in string in c++

#include<iostream>
using namespace std;
main() {
   string my_str = "Hello World";
   for(int i = 0; i<my_str.length(); i++) {
      cout << my_str.at(i) << endl; //get character at position i
   }
}

Example 2: c++ read each char of string

std::string str = ???;
for(std::string::iterator it = str.begin(); it != str.end(); ++it) {
    do_things_with(*it);
}