std::map<Key,T,Compare,Allocator>::value_compare

 

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class value_compare;

std::map::value_compare is a function object that compares objects of type std::map::value_type (key-value pairs) by comparing of the first components of the pairs.

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)	value_type
second_argument_type (deprecated in C++17)(removed in C++20)	value_type

These member types are obtained via publicly inheriting std::binary_function<value_type, value_type, bool>.

(until C++11)

Protected member objects

Compare comp

the stored comparator (protected member object)

Member functions

(constructor)	constructs a new value_compare object (protected member function)
operator()	compares two values of type value_type (public member function)

std::map<Key,T,Compare,Alloc>::value_compare::value_compare

protected: value_compare( Compare c );

Initializes the internal instance of the comparator to c.

Parameters

c

-

comparator to assign

std::map<Key,T,Compare,Alloc>::value_compare::operator()

bool operator()( const value_type& lhs, const value_type& rhs ) const;

Compares lhs.first and rhs.first by calling the stored comparator.

Parameters

lhs, rhs

-

values to compare

Return value

comp(lhs.first, rhs.first).

Exceptions

May throw implementation-defined exceptions.