5. operator!=

    • Class / Function / Type

      std::

    • Header file

      <>

    • Other / All

    crsearch v3.0.23

    最終更新日時(UTC):
    が更新

    履歴 編集

    function template
    <string>

    std::operator!=

    namespace std {
  // operator==により、以下の演算子が使用可能になる (C++20)
  template <class CharT, class Traits, class Allocator>
  bool
    operator!=(const basic_string<CharT, Traits, Allocator>& a,
               const basic_string<CharT, Traits, Allocator>& b);          // (1) C++03
  template <class CharT, class Traits, class Allocator>
  bool
    operator!=(const basic_string<CharT, Traits, Allocator>& a,
               const basic_string<CharT, Traits, Allocator>& b) noexcept; // (1) C++14
  template <class CharT, class Traits, class Allocator>
  constexpr bool
    operator!=(const basic_string<CharT, Traits, Allocator>& a,
               const basic_string<CharT, Traits, Allocator>& b) noexcept; // (1) C++20


  template <class CharT, class Traits, class Allocator>
  bool
    operator!=(const CharT* a,
               const basic_string<CharT, Traits, Allocator>& b); // (2) C++03
  template <class CharT, class Traits, class Allocator>
  constexpr bool
    operator!=(const CharT* a,
               const basic_string<CharT, Traits, Allocator>& b); // (2) C++20

  template <class CharT, class Traits, class Allocator>
  bool
    operator!=(const basic_string<CharT, Traits, Allocator>& a,
               const CharT* b);                                  // (3) C++03
  template <class CharT, class Traits, class Allocator>
  constexpr bool
    operator!=(const basic_string<CharT, Traits, Allocator>& a,
               const CharT* b);                                  // (3) C++20
}

    概要

    basic_stringオブジェクトの非等値比較を行う。

    要件

    • (3) パラメータbが、Traits::length(b) + 1の要素数を持つCharT文字型の配列を指していること

    戻り値

    • (1) !(a == b)
    • (2) b != a
    • (3) a.compare(b) != 0

    例

    #include <iostream>
#include <string>

int main()
{
  std::string a = "abc";
  std::string b = "abcd";

  if (a != b) {
    std::cout << "not equal" << std::endl;
  }
  else {
    std::cout << "equal" << std::endl;
  }
}

    出力

    not equal

    参照