how to find length of the string in cpp code example

Example 1: length of string c++

// string::length
#include <iostream>
#include <string>

int main ()
{
  std::string str ("Test string");
  std::cout << "The size of str is " << str.length() << " bytes.\n";
  return 0;
}

Example 2: create a string of length c++

#include <string>
#include <iostream>

int main()
{
    std::string s(21, '*');

    std::cout << s << std::endl;

    return 0;
}