op_equal.md

operator==

• system_error[meta header]
• std[meta namespace]
• function[meta id-type]
• cpp11[meta cpp]

namespace std {
  bool operator==(const error_code& lhs, const error_code& rhs) noexcept;           // (1) C++11
  bool operator==(const error_code& lhs, const error_condition& rhs) noexcept;      // (2) C++11
  bool operator==(const error_condition& lhs, const error_condition& rhs) noexcept; // (3) C++11

  // (2)により以下のオーバーロードが使用可能になる (C++20)
  bool operator==(const error_condition& lhs, const error_code& rhs) noexcept;      // (4) C++11
}

• error_code[link /reference/system_error/error_code.md]
• error_condition[link /reference/system_error/error_condition.md]

概要

error_code, error_conditionの等値比較を行う

戻り値

• (1) :

  lhs.category() == rhs.category() && lhs.value() == rhs.value()

  • category()[link error_code/category.md]
  • value()[link error_code/value.md]

• (2) :

  lhs.category().equivalent(lhs.value(), rhs) || rhs.category().equivalent(lhs, rhs.value())

  • lhs.category()[link error_code/category.md]
  • rhs.category()[link error_condition/category.md]
  • equivalent[link error_category/equivalent.md]
  • lhs.value()[link error_code/value.md]
  • rhs.value()[link error_condition/value.md]

• (3) :

  lhs.category() == rhs.category() && lhs.value() == rhs.value()

  • category()[link error_condition/category.md]
  • value()[link error_condition/value.md]

• (4) :

  rhs.category().equivalent(rhs.value(), lhs) || lhs.category().equivalent(rhs, lhs.value())

  • lhs.category()[link error_condition/category.md]
  • rhs.category()[link error_code/category.md]
  • equivalent[link error_category/equivalent.md]
  • lhs.value()[link error_condition/value.md]
  • rhs.value()[link error_code/value.md]

例外

投げない

例

#include <iostream>
#include <system_error>

int main()
{
  std::error_code ec1 = std::make_error_code(std::errc::invalid_argument);
  std::error_code ec2 = std::make_error_code(std::errc::permission_denied);
  std::error_condition ed1 = std::make_error_condition(std::errc::invalid_argument);
  std::error_condition ed2 = std::make_error_condition(std::errc::permission_denied);

  std::cout << std::boolalpha;

  std::cout << "error_code == error_code : " << (ec1 == ec1) << std::endl;
  std::cout << "error_code == error_code : " << (ec1 == ec2) << std::endl;

  std::cout << "error_code == error_condition : " << (ec1 == ed1) << std::endl;
  std::cout << "error_code == error_condition : " << (ec1 == ed2) << std::endl;

  std::cout << "error_condition == error_condition : " << (ed1 == ed1) << std::endl;
  std::cout << "error_condition == error_condition : " << (ed1 == ed2) << std::endl;

}

• std::error_code[link error_code.md]
• std::make_error_code[link make_error_code.md]
• std::errc::invalid_argument[link errc.md]
• std::errc::permission_denied[link errc.md]
• std::error_condition[link error_condition.md]
• std::make_error_condition[link make_error_condition.md]

出力

error_code == error_code : true
error_code == error_code : false
error_code == error_condition : true
error_code == error_condition : false
error_condition == error_condition : true
error_condition == error_condition : false

バージョン

言語

• C++11

処理系

• Clang: ??
• GCC: 4.7.0 [mark verified]
• ICC: ??
• Visual C++: 2010 [mark verified]

参照

• P1614R2 The Mothership has Landed
  • C++20での三方比較演算子の追加と、関連する演算子の自動導出