#include <iostream>

#include <string>


int main() {

  // Create a string object

  std::string str = "Hello, World!";


  // Get the length of the string

  std::cout << "The length of the string is: " << str.length() << std::endl;


  // Find the position of a substring within the string

  std::cout << "The position of 'World' in the string is: " << str.find("World") << std::endl;


  // Replace a substring within the string

  str.replace(str.find("World"), 5, "Universe");

  std::cout << "The modified string is: " << str << std::endl;


  // Extract a substring from the string

  std::string substr = str.substr(str.find(",") + 2, 6);

  std::cout << "The extracted substring is: " << substr << std::endl;


  return 0;

}

output :

The length of the string is: 14
The position of 'World' in the string is: 7
The modified string is: Hello, Universe!
The extracted substring is: Universe