std::map::find – cppreference.com

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`iterator find( const Key& key );`

`const_iterator find( const Key& key ) const;`

Sucht ein Element mit Schlüssel key.

Original:

Finds an element with key key.

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Parameter

key

Schlüsselwert des Elements zu suchen

Original:

key value of the element to search for

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Rückgabewert

Iterator auf ein Element mit Schlüssel key. Wenn kein solches Element gefunden wird, past-the-Ende (siehe end()) Iterator zurückgegeben .

Original:

Iterator to an element with key key. If no such element is found, past-the-end (see end()) iterator is returned.

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Komplexität

Logarithmic in the size of the container.

Siehe auch


	liefert die Anzahl der Elemente zu einem Schlüssel Original: returns the number of elements matching specific key The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) [edit]

	Bandbreite der Rendite von Elementen übereinstimmenden eine bestimmte Taste Original: returns range of elements matching a specific key The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) [edit]

Beispiel

Demonstrates the risk of accessing non-existing elements via operator [].

#include <string>
#include <iostream>
#include <map>

int main()
{
    typedef std::map<std::string,int>  mapT;

    mapT my_map;
    my_map["first"]=  11;
    my_map["second"]= 23;
    
    mapT::iterator  it= my_map.find("first");
    if( it != my_map.end() ) std::cout << "A: " << it->second << "\n";

    it= my_map.find("third");
    if( it != my_map.end() ) std::cout << "B: " << it->second << "\n";

    // Accessing a non-existing element creates it
    if( my_map["third"] == 42 ) std::cout << "Oha!\n";
    
    it= my_map.find("third");
    if( it != my_map.end() ) std::cout << "C: " << it->second << "\n";
  
    return 0;
}

Output: