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<unordered_map>

C++11
unordered_map
C++11
unordered_multimap

unordered_map

C++11
unordered_map::~unordered_map
C++11
unordered_map::unordered_map
member functions
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  unordered_map::emplace_hint
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  unordered_map::end
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  unordered_map::equal_range
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  unordered_map::erase
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  unordered_map::find
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  unordered_map::get_allocator
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  unordered_map::hash_function
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  unordered_map::insert
- C++11
  unordered_map::key_eq
- C++11
  unordered_map::load_factor
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  unordered_map::max_load_factor
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  unordered_map::max_size
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  unordered_map::operator=
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  unordered_map::size
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  unordered_map::swap
non-member overloads
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  operators (unordered_map)
- C++11
  swap (unordered_map)

public member type

<unordered_map>

std::unordered_map::key_eq

key_equal key_eq() const;

Get key equivalence predicate

Returns the key equivalence comparison predicate used by the unordered_map container.

The key equivalence comparison is a predicate that takes two arguments of the key type and returns a bool value indicating whether they are to be considered equivalent. It is adopted by the container on construction (see unordered_map's constructor for more info). By default, it is equal_to<key_type>, which returns the same as applying the equal-to operator (==) to the arguments.

Parameters

none

Return Value

The key equality comparison object.

Member type key_equal is the type of the key equality comparison predicate used by the container, defined in unordered_map as an alias of its fourth template parameter (Pred).

Example

// unordered_map::key_eq
#include <iostream>
#include <string>
#include <unordered_map>

int main ()
{
  std::unordered_map<std::string,std::string> mymap;

  bool case_insensitive = mymap.key_eq()("test","TEST");

  std::cout << "mymap.key_eq() is ";
  std::cout << ( case_insensitive ? "case insensitive" : "case sensitive" );
  std::cout << std::endl;

  return 0;
}

Output:

mymap.key_eq() is case sensitive

Complexity

Constant.

Iterator validity

No changes.

See also

unordered_map::hash_function: Get hash function (public member type)

unordered_map::get_allocator: Get allocator (public member function)

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