C++20 (or C++2a), C++ 2020, Cpp 2020, g++ 2020

Subject: C++ 2020

4
contracts example

/**

C++ 2020 contracts

$ g++ -fcontracts -std=c++20 cpp2020_contracts.cpp

**/

 

#include <iostream>

using namespace std;

void f(int x)

[[ pre: x >= 0 ]]  // contracts line

{

}

int main()

{

  f (1);  // ok

  f (0);  // ok

  f (-1); // oops

  return 0;

}

3
ranges example

#include <iostream>

#include <ranges>

int main() {

    for(int i : std::views::iota(1,4)) {

        std::cout << i << " ";  // 1 2 3

    }

    std::cout << "\n";

    return EXIT_SUCCESS; 

}


2
The best parts of C++ 2020, the key features of C++ 2020

The big five feature updates of C++ 2020
- concepts
- coroutines
- ranges
- modules
- text formatting


1
Web links

C++ module, export, import
https://en.cppreference.com/w/cpp/language/modules

Compilers support for C++20
https://en.cppreference.com/w/cpp/compiler_support/20

Online C++ 2020 compiler godbolt or compiler explorer
https://gcc.godbolt.org/
Menu > Add new > Execution only
Tab on the Compilation
Select: x86-64 gcc (trunk)
Compiler options: type: -std=c++2a