std::map<Key,T,Compare,Allocator>::value_compare
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class value_compare;
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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 |
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These member types are obtained via publicly inheriting std::binary_function<value_type, value_type, bool>. |
(until C++11) |
Protected member objects
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Compare comp
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the stored comparator (protected member object) |
Member functions
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(constructor)
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constructs a new value_compare object(protected member function) |
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operator()
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compares two values of type value_type(public member function) |
std::map<Key,T,Compare,Alloc>::value_compare::value_compare
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protected:
value_compare( Compare c ); |
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Initializes the internal instance of the comparator to c.
Parameters
| c | - | comparator to assign |
std::map<Key,T,Compare,Alloc>::value_compare::operator()
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bool operator()( const value_type& lhs, const value_type& rhs ) const;
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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.