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std::unordered_map::contains

bool contains( const Key& key ) const;
 (1) (since C++20)
1) Checks if there is an element with key equivalent to key in the container.

Parameters

key - key value of the element to search for

Return value

true if there is such an element, otherwise false.

Complexity

Constant on average, worst case linear in the size of the container.

Example

#include <iostream>
#include <unordered_map>
 
int main()
{  
    std::unordered_map<int,char> example = {{1,'a'},{2,'b'}};
 
    if(example.contains(2)) {
        std::cout << "Found\n";
    } else {
        std::cout << "Not found\n";
    }
}

Output:

Found

See also

finds element with specific key
(public member function)
returns the number of elements matching specific key
(public member function)
returns range of elements matching a specific key
(public member function)

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