basics/card.cpp

The following code example is taken from the book
C++ Move Semantics - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2020
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include "card.hpp"
#include <iostream>
#include <string>
#include <vector>

void print(const Card& c)
{
  std::string val{c.getValue()};
  auto pos = val.find("-of-");
  auto p2 = pos + 4;
  std::cout << val.substr(0, pos) << ' '
            << val.substr(pos+4) << '\n';
}

int main()
{
  std::vector<Card> deck;

  for (auto suit : {"clubs", "spades", "hearts", "diamonds"}) {
    for (auto rank : {"seven", "eight", "nine", "ten",
                      "jack", "queen", "king", "ace"}) {
      deck.push_back(rank + std::string{"-of-"} + suit);
    }
  }

  for (const auto& c : deck) {
    std::cout << c << '\n';
  }
  print(deck[0]);                   // passing a valid object

  Card c{std::move(deck[0])};       // deck[0] has invalid state
  print(deck[0]);                   // passing an object with broken invariant
  deck[0] = Card{"ace-of-hearts"};  // deck[0] is valid again
  print(deck[0]);                   // passing a valid object
}