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      std::map<Key,T,Compare,Allocator>::contains

      From cppreference.com
      <cpp‎ |container‎ |map

      [edit template]
       
       
       
      std::map
      Member functions
      Non-member functions
      (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
      Deduction guides(C++17)
       
      bool contains(const Key& key)const;
      		 (1)(since C++20)
      (constexpr since C++26)
      template<class K>
      bool contains(const K& x)const;
      		 (2)(since C++20)
      (constexpr since C++26)
      1) Checks if there is an element with key equivalent tokey in the container.
      2) Checks if there is an element with key that compares equivalent tox.
      This overload participates in overload resolution only ifCompare istransparent. It allows calling this function without constructing an instance ofKey.

      Contents

      [edit]Parameters

      key - key value of the element to search for
      x - a value of any type that can be transparently compared with a key

      [edit]Return value

      true if there is such an element, otherwisefalse.

      [edit]Complexity

      Logarithmic in the size of the container.

      [edit]Example

      Run this code
      #include <iostream>#include <map> int main(){std::map<int,char> example{{1,'a'},{2,'b'}}; for(int x:{2,5})if(example.contains(x))std::cout<< x<<": Found\n";elsestd::cout<< x<<": Not found\n";}

      Output:

      2: Found5: Not found

      [edit]See also

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