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cpp/algorithm/qsort : Différence entre versions

De cppreference.com
< cpp‎ | algorithm
m (Remplacement du texte — « <code terminal> » par « <syntaxhighlight lang="text"> »)
m (Use {{lc}}. Update links. Various fixes.)
 
(10 révisions intermédiaires par 3 utilisateurs sont masquées)
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{{title|qsort}}
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Syntaxe :
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title|qsort}}
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<syntaxhighlight lang="cpp">
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le tableau 'contient éléments de taille. |est pour '..
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    #include <cstdlib>
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    void qsort( void *buf, size_t nb, size_t taille, int (*compare)(const void*, const void *) );
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</syntaxhighlight>
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La fonction qsort() trie le tableau ''buf'' (qui contient ''nb'' éléments, chacun de
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taille ''taille'') en utilisant l'algorithme [[cpp/http:''fr.wikipedia.org/wiki/Tri_rapide | Quicksort]].
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La fonction ''compare'' est utilisée pour comparer les élément de ''buf'' et doit retourner une
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valeur négative si le premier argument est inférieur au second, zéro si les deux éléments sont égaux
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et une valeur positive si le premier est supérieur au second. ''qsort()'' trie le ''buf'' dans l'ordre
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croissant.
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Par exemple, le bout de code ci-dessous utilise ''qsort()'' pour trier un tableau d'entiers :
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le tableau
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d'
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<syntaxhighlight lang="cpp">
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===
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  int compare_ints( const void* a, const void* b ) {  // fonction de comparaison
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()()}
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    int* arg1 = (int*) a;
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    int* arg2 = (int*) b;
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    if( *arg1 < *arg2 ) return -1;
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    else if( *arg1 == *arg2 ) return 0;
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    else return 1;
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  }
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  int tab[] = { -2, 99, 0, -743, 2, 3, 4 };
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  int taille_tab= 7;
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{, , }
  
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  ...
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  printf( "Avant le tri : " );
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  for( int i = 0; i < taille_tab; i++ ) {
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{
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    printf( "%d ", tab[i] );
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  }
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}
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  printf( "\n" );
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  qsort( tab, taille_tab, sizeof(int), compare_ints );
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qsort
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  printf( "Après le tri : " );
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[]
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  for( int i = 0; i < taille_tab; i++ ) {
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/
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    printf( "%d ", tab[i] );
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:
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  }
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:/
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  printf( "\n" );
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[[cpp/algorithm/]]
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</syntaxhighlight>
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[[cpp/algorithm/
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/algorithm/]]
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À l'exécution ce code, voici ce qu'on observer sur la sortie standard :
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<syntaxhighlight lang="text">
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  Avant le tri : -2 99 0 -743 2 3 4
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  Après le tri : -743 -2 0 2 3 4 99
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</syntaxhighlight>
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Sujets connexes : [[cpp/algorithm/bsearch | bsearch]], [[cpp/algorithm/sort | stl/algorithm/sort]]
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Version actuelle en date du 2 juillet 2013 à 04:27

This page has been machine-translated from the English version of the wiki using Google Translate.

The translation may contain errors and awkward wording. Hover over text to see the original version. You can help to fix errors and improve the translation. For instructions click here.

Click here for the English version of this page

 
C++
 
Bibliothèque d'algorithmes
Fonctions
Original:
Functions
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Non-modification de la séquence des opérations
Original:
Non-modifying sequence operations
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Modification de la séquence des opérations
Original:
Modifying sequence operations
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Des opérations de partitionnement
Original:
Partitioning operations
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Opérations de tri (sur les gammes triés)
Original:
Sorting operations (on sorted ranges)
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is_sorted (C++11)
is_sorted_until (C++11)
sort
Opérations binaires de recherche (sur les gammes triés)
Original:
Binary search operations (on sorted ranges)
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Définir les opérations (sur les gammes triés)
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Set operations (on sorted ranges)
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Opérations Heap
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Heap operations
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Minimum / maximum de fonctionnement
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Minimum/maximum operations
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Opérations numériques
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Numeric operations
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Bibliothèque C
Original:
C library
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qsort
 
Déclaré dans l'en-tête <cstdlib>
void qsort( const void *ptr, size_t count, size_t size,
            int (*comp)(const void *, const void *) );
Trie le tableau donné pointé par ptr dans l'ordre croissant. Le tableau contient des éléments count de size taille. Fonction pointée par comp est utilisé pour la comparaison d'objets .
Original:
Sorts the given array pointed to by ptr in ascending order. The array contains count elements of size size. Function pointed to by comp is used for object comparison.
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Sommaire

[modifier] Paramètres

ptr -
pointeur vers le tableau à trier
Original:
pointer to the array to sort
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count -
nombre d'éléments dans le tableau
Original:
number of element in the array
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size -
taille de chaque élément dans le tableau en octets
Original:
size of each element in the array in bytes
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comp - comparison function which returns ​a negative integer value if the first argument is less than the second,

a positive integer value if the first argument is greater than the second and zero if the arguments are equal.
The signature of the comparison function should be equivalent to the following:

 int cmp(const void *a, const void *b);

The function must not modify the objects passed to it.

​

[modifier] Retourne la valeur

(Aucun)
Original:
(none)
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[modifier] Notes

Le type des éléments du tableau doit être un type trivial, sinon le comportement est indéfini .
Original:
The type of the elements of the array must be a trivial type, otherwise the behavior is undefined.
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[modifier] Exemple

Le code suivant trie un tableau d'entiers en utilisant qsort() .
Original:
The following code sorts an array of integers using qsort().
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#include <iostream>
#include <cstdlib>
 
int compare_ints(const void* a, const void* b)   // comparison function
{
    int* arg1 = (int*) a;
    int* arg2 = (int*) b;
    if (*arg1 < *arg2) return -1;
    else if (*arg1 == *arg2) return 0;
    else return 1;
}
 
int main()
{
    int a[] = { -2, 99, 0, -743, 2, 3, 4 };
    int size = 7;
 
    std::qsort(a, size, sizeof(int), compare_ints);
 
    for (int i = 0; i < size; i++) {
        std::cout << a[i] << " ";
    }
    std::cout << '\n';
}

Résultat : 

-743 -2 0 2 3 4 99

[modifier] Voir aussi
recherche un tableau pour un élément de type non spécifié
Original:
searches an array for an element of unspecified type
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(fonction) [edit]
trie une plage dans l'ordre ascendant
Original:
sorts a range into ascending order
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(fonction générique) [edit]
(C++11)
vérifie si un type est trivial
Original:
checks if a type is trivial
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(classe générique) [edit]
C documentation for qsort
Récupérée de « https://fr.cppreference.com/mwiki/index.php?title=cpp/algorithm/qsort&oldid=47542 »