std::map::value_compare

 

C++

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Technical Specifications

 

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std::map

Member functions

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Element access

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map::beginmap::cbegin (C++11)

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Lookup

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Observers

map::key_comp

map::value_comp

 

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)	bool
first_argument_type(deprecated in C++17)	value_type
second_argument_type(deprecated in C++17)	value_type

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

(none)