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

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
(until C++20)

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).

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