std::equal_to (3) - Linux Manuals

std::equal_to: std::equal_to


std::equal_to - std::equal_to


Defined in header <functional>
template< class T > (until C++14)
struct equal_to;
template< class T = void > (since C++14)
struct equal_to;

Function object for performing comparisons. Unless specialised, invokes operator== on type T.


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 argument and return types (since C++14)
equal_to<void> (class template specialization)

Member types

Type Definition (until C++20)
result_type(deprecated in C++17) bool
first_argument_type(deprecated in C++17) T
second_argument_type(deprecated in C++17) T

Member functions

           checks if the arguments are equal
operator() (public member function)


bool operator()( const T& lhs, const T& rhs ) const; (until C++14)
constexpr bool operator()( const T& lhs, const T& rhs ) const; (since C++14)

Checks whether lhs is equal to rhs.


lhs, rhs - values to compare

Return value

true if lhs == rhs, false otherwise.



Possible implementation

  constexpr bool operator()(const T &lhs, const T &rhs) const
      return lhs == rhs;