public member type
<unordered_set>

std::unordered_set::key_eq

key_equal key_eq() const;
Get key equivalence predicate
Returns the key equivalence comparison predicate used by the unordered_set container.

The key equivalence comparison is a predicate that takes the value of two elements as arguments and returns a bool value indicating whether they are to be considered equivalent. It is adopted by the container on construction (see unordered_set'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_set as an alias of its third template parameter (Pred).

Example

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

int main ()
{
  std::unordered_set<std::string> myset;

  bool case_insensitive = myset.key_eq()("checking","CHECKING");

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

  return 0;
}


Output:
myset.key_eq() is case sensitive


Complexity

Constant.

Iterator validity

No changes.

See also

  • 9281021542 2018-02-20
  • 632231541 2018-02-20
  • 9751491540 2018-02-20
  • 8333621539 2018-02-20
  • 995001538 2018-02-20
  • 6477441537 2018-02-20
  • 511981536 2018-02-19
  • 2072881535 2018-02-19
  • 6024461534 2018-02-19
  • 7594061533 2018-02-19
  • 9311341532 2018-02-19
  • 4928331531 2018-02-19
  • 38561530 2018-02-19
  • 7776611529 2018-02-19
  • 3038041528 2018-02-19
  • 9566341527 2018-02-19
  • 3936031526 2018-02-19
  • 9531111525 2018-02-19
  • 291211524 2018-02-19
  • 8962001523 2018-02-19