20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.6 Arithmetic operations [arithmetic.operations]

The library provides basic function object classes for all of the arithmetic operators in the language ([expr.mul], [expr.add]).

20.14.6.1 Class template plus [arithmetic.operations.plus]

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template<class T = void> struct plus {
  constexpr T operator()(const T& x, const T& y) const;
};

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constexpr T operator()(const T& x, const T& y) const;

Returns: x + y.

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template<> struct plus<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) + std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) + std::forward<U>(u));

Returns: std::forward<T>(t) + std::forward(u).

20.14.6.2 Class template minus [arithmetic.operations.minus]

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template<class T = void> struct minus {
  constexpr T operator()(const T& x, const T& y) const;
};

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constexpr T operator()(const T& x, const T& y) const;

Returns: x - y.

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template<> struct minus<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) - std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) - std::forward<U>(u));

Returns: std::forward<T>(t) - std::forward(u).

20.14.6.3 Class template multiplies [arithmetic.operations.multiplies]

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template<class T = void> struct multiplies {
  constexpr T operator()(const T& x, const T& y) const;
};

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constexpr T operator()(const T& x, const T& y) const;

Returns: x * y.

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template<> struct multiplies<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) * std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) * std::forward<U>(u));

Returns: std::forward<T>(t) * std::forward(u).

20.14.6.4 Class template divides [arithmetic.operations.divides]

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template<class T = void> struct divides {
  constexpr T operator()(const T& x, const T& y) const;
};

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constexpr T operator()(const T& x, const T& y) const;

Returns: x / y.

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template<> struct divides<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) / std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) / std::forward<U>(u));

Returns: std::forward<T>(t) / std::forward(u).

20.14.6.5 Class template modulus [arithmetic.operations.modulus]

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template<class T = void> struct modulus {
  constexpr T operator()(const T& x, const T& y) const;
};

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constexpr T operator()(const T& x, const T& y) const;

Returns: x % y.

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template<> struct modulus<void> {
  template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) % std::forward<U>(u));

  using is_transparent = unspecified;
};

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template<class T, class U> constexpr auto operator()(T&& t, U&& u) const
    -> decltype(std::forward<T>(t) % std::forward<U>(u));

Returns: std::forward<T>(t) % std::forward(u).

20.14.6.6 Class template negate [arithmetic.operations.negate]

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template<class T = void> struct negate {
  constexpr T operator()(const T& x) const;
};

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constexpr T operator()(const T& x) const;

Returns: -x.

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template<> struct negate<void> {
  template<class T> constexpr auto operator()(T&& t) const
    -> decltype(-std::forward<T>(t));

  using is_transparent = unspecified;
};

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template<class T> constexpr auto operator()(T&& t) const
    -> decltype(-std::forward<T>(t));

Returns: -std::forward<T>(t).