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std::multimap contains() method

// (1) Const version only
bool contains( const Key& key ) const;

// (2) Const version only
template< class K >
bool contains( const K& x ) const;
  • (1) Checks if there is an element with key equivalent to key in the container.
  • (2) Checks if there is an element with key that compares equivalent to the value x. This overload participates in overload resolution only if the qualified-id Compare::is_transparent is valid and denotes a type. It allows calling this function without constructing an instance of Key.

Parameters

  • key - key value of the elements to count
  • x - a value of any type that can be transparently compared with a key

Return value

true if these is such an element, otherwise false.

Complexity

Logarithmic in the size of the container - O(log size()).

Exceptions

(none)

Notes

Feature testing macro: __cpp_lib_generic_associative_lookup (for overloads (3) and (4)).

Examples

Main.cpp
#include <iostream>
#include <map>

int main()
{
std::multimap<int,char> example = {{1,'a'},{2,'b'}};

for(int x: {2, 5}) {
if(example.contains(x)) {
std::cout << x << ": Found\n";
} else {
std::cout << x << ": Not found\n";
}
}
}
Output
2: Found
5: Not found
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
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std::multimap contains() method

// (1) Const version only
bool contains( const Key& key ) const;

// (2) Const version only
template< class K >
bool contains( const K& x ) const;
  • (1) Checks if there is an element with key equivalent to key in the container.
  • (2) Checks if there is an element with key that compares equivalent to the value x. This overload participates in overload resolution only if the qualified-id Compare::is_transparent is valid and denotes a type. It allows calling this function without constructing an instance of Key.

Parameters

  • key - key value of the elements to count
  • x - a value of any type that can be transparently compared with a key

Return value

true if these is such an element, otherwise false.

Complexity

Logarithmic in the size of the container - O(log size()).

Exceptions

(none)

Notes

Feature testing macro: __cpp_lib_generic_associative_lookup (for overloads (3) and (4)).

Examples

Main.cpp
#include <iostream>
#include <map>

int main()
{
std::multimap<int,char> example = {{1,'a'},{2,'b'}};

for(int x: {2, 5}) {
if(example.contains(x)) {
std::cout << x << ": Found\n";
} else {
std::cout << x << ": Not found\n";
}
}
}
Output
2: Found
5: Not found
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.