string iterator in c 2b 2b

1#include<iostream>
2using namespace std;
3main() {
4   string my_str = "Hello World";
5   for(int i = 0; i<my_str.length(); i++) {
6      cout << my_str.at(i) << endl; //get character at position i
7   }
8}

1std::string s("Hello world");
2
3for (char & c : s)
4{
5    std::cout << "One character: " << c << "\n";
6    c = '*';
7}
8

1// string::begin/end
2#include <iostream>
3#include <string>
4
5int main ()
6{
7  std::string str ("Test string");
8  for ( std::string::iterator it=str.begin(); it!=str.end(); ++it)
9    std::cout << *it << endl;
10  std::cout << '\n';
11
12  return 0;
13}