std::string从C++20支持的新Operations

https://en.cppreference.com/w/cpp/string/basic_string

#include <iostream>
#include <string>
#include <format>

void test_01()
{
    int val = std::stoi("101");
    std::cout << std::format("{}\n", val);  // 101

    std::string str("Hello C++20!");
    if(str.ends_with("C++20!")){
        std::cout << std::format("{} ends with \"{}\"\n",str, "C++20!");  // Hello C++20! ends with "C++20!"
    }
    if(str.starts_with("Hello")){
        std::cout << std::format("{} starts with \"{}\"\n",str, "Hello");  // Hello C++20! ends with "C++20!"
    }
    if(str.contains("C++23")){
        std::cout << std::format("{} contains \"{}\"\n",str, "C++23");
    }
    else {
        // std::basic_string<CharT,Traits,Allocator>::contains is supported from "C++23".
        std::cout << std::format("std::basic_string<CharT,Traits,Allocator>::contains is supported from \"{}\".\n", "C++23");
    }
}
 
int main()
{
    test_01();
}