set::erase

Article
06/09/2015

Supprime un élément ou une plage d'éléments dans un jeu d'emplacements spécifiés ou supprime les éléments qui correspondent à une clé spécifiée.

iterator erase(
   const_iterator Where
);
iterator erase(
   const_iterator First,
   const_iterator Last
);
size_type erase(
   const key_type& Key
);

Paramètres

Where
Position de l'élément à supprimer.
First
Position du premier élément à supprimer.
Last
Position juste au delà du dernier élément à supprimer.
Key
Valeur clé de l'élément à supprimer.

Valeur de retour

Pour les deux premières fonctions membres, un itérateur bidirectionnel qui indique le premier élément restant au delà de tous les éléments supprimés, ou un élément qui est la fin du jeu si aucun élément n'existe.

Pour la troisième fonction membre, retourne le nombre d'éléments qui ont été supprimés du jeu.

Exemple

// set_erase.cpp
// compile with: /EHsc
#include <set>
#include <string>
#include <iostream>
#include <iterator> // next() and prev() helper functions

using namespace std;

using myset = set<string>;

void printset(const myset& s) {
    for (const auto& iter : s) {
        cout << " [" << iter << "]";
    }
    cout << endl << "size() == " << s.size() << endl << endl;
}

int main()
{
    myset s1;

    // Fill in some data to test with, one at a time
    s1.insert("Bob");
    s1.insert("Robert");
    s1.insert("Bert");
    s1.insert("Rob");
    s1.insert("Bobby");

    cout << "Starting data of set s1 is:" << endl;
    printset(s1);
    // The 1st member function removes an element at a given position
    s1.erase(next(s1.begin()));
    cout << "After the 2nd element is deleted, the set s1 is:" << endl;
    printset(s1);

    // Fill in some data to test with, one at a time, using an intializer list
    myset s2{ "meow", "hiss", "purr", "growl", "yowl" };

    cout << "Starting data of set s2 is:" << endl;
    printset(s2);
    // The 2nd member function removes elements
    // in the range [First, Last)
    s2.erase(next(s2.begin()), prev(s2.end()));
    cout << "After the middle elements are deleted, the set s2 is:" << endl;
    printset(s2);

    myset s3;

    // Fill in some data to test with, one at a time, using emplace
    s3.emplace("C");
    s3.emplace("C#");
    s3.emplace("D");
    s3.emplace("D#");
    s3.emplace("E");
    s3.emplace("E#");
    s3.emplace("F");
    s3.emplace("F#");
    s3.emplace("G");
    s3.emplace("G#");
    s3.emplace("A");
    s3.emplace("A#");
    s3.emplace("B");

    cout << "Starting data of set s3 is:" << endl;
    printset(s3);
    // The 3rd member function removes elements with a given Key
    myset::size_type count = s3.erase("E#");
    // The 3rd member function also returns the number of elements removed
    cout << "The number of elements removed from s3 is: " << count << "." << endl;
    cout << "After the element with a key of \"E#\" is deleted, the set s3 is:" << endl;
    printset(s3);
}

Sortie

Starting data of set s1 is:
 [Bert] [Bob] [Bobby] [Rob] [Robert]
size() == 5

After the 2nd element is deleted, the set s1 is:
 [Bert] [Bobby] [Rob] [Robert]
size() == 4

Starting data of set s2 is:
 [growl] [hiss] [meow] [purr] [yowl]
size() == 5

After the middle elements are deleted, the set s2 is:
 [growl] [yowl]
size() == 2

Starting data of set s3 is:
 [A] [A#] [B] [C] [C#] [D] [D#] [E] [E#] [F] [F#] [G] [G#]
size() == 13

The number of elements removed from s3 is: 1.
After the element with a key of "E#" is deleted, the set s3 is:
 [A] [A#] [B] [C] [C#] [D] [D#] [E] [F] [F#] [G] [G#]
size() == 12