std::map value_compare

since C++98

class value_compare;

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

Member types

pub	Type	Definition
pub	result_type (deprecated in C++17) (removed in C++20)	bool
pub	first_argument_type (deprecated in C++17) (removed in C++20)	value_type
pub	second_argument_type (deprecated in C++17) (removed in C++20)	value_type

until C++11

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

Protected member objects

prot

Compare comp

the stored comparator

Member functions

prot

(constructor)

constructs a new value_compare object

protected:
value_compare( Compare c );

Initializes the internal instance of the comparator to c.

Parameters

• c - comparator to assign

pub

operator()

compares two values of type value_type

// Const version only
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.