std::equal_to - cppreference.com (original) (raw)
| Defined in header | | | | -------------------------------------------------------------------------------------- | | ------------- | | template< class T > struct equal_to; | | (until C++14) | | template< class T = void > struct equal_to; | | (since C++14) |
Function object for performing comparisons. Unless specialised, invokes operator== on type T.
Contents
[edit] Specializations
| The standard library provides a specialization of std::equal_to when T is not specified, which leaves the parameter types and return type to be deduced. function object implementing x == y deducing parameter and return types (class template specialization) [edit] | (since C++14) |
|---|
[edit] Member types
| Type | Definition |
|---|---|
| result_type (deprecated in C++17)(removed in C++20) | bool |
| first_argument_type (deprecated in C++17)(removed in C++20) | T |
| second_argument_type (deprecated in C++17)(removed in C++20) | T |
| These member types are obtained via publicly inheriting std::binary_function<T, T, bool>. | (until C++11) |
|---|
[edit] Member functions
| | checks if the arguments are equal (public member function) | | --------------------------------------------------------------- |
std::equal_to::operator()
| bool operator()( const T& lhs, const T& rhs ) const; | | (constexpr since C++14) | | ---------------------------------------------------- | | ----------------------- |
Checks whether lhs is equal to rhs.
Parameters
| lhs, rhs | - | values to compare |
|---|
Return value
true if lhs == rhs, false otherwise.
[edit] Exceptions
May throw implementation-defined exceptions.
Possible implementation
constexpr bool operator()(const T& lhs, const T& rhs) const { return lhs == rhs; }