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qsort

Da cppreference.com.
< c‎ | algorithm

Defined in header <stdlib.h>
void qsort( const void *ptr, size_t count, size_t size,
            int (*comp)(const void *, const void *) );
Ordina l'array dato puntato da ptr in ordine crescente. La matrice contiene elementi count di size dimensioni. Funzione puntato da comp viene utilizzato per confronto oggetto.
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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Indice

[modifica] Parametri

ptr -
puntatore alla matrice da ordinare
Original:
pointer to the array to sort
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count -
numero di elemento della matrice
Original:
number of element in the array
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size -
dimensione di ciascun elemento della matrice in byte
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.

[modifica] Valore di ritorno

(Nessuno)
Original:
(none)
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[modifica] Esempio

Il codice seguente ordina un array di numeri interi che utilizzano qsort()
Original:
The following code sorts an array of integers using qsort()
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#include <stdio.h>
#include <stdlib.h>
 
int compare_ints(const void* a, const void* b)
{
    const int *arg1 = a;
    const int *arg2 = b;
 
    return *arg1 - *arg2;
}
 
int main(void)
{
    int i;
    int ints[] = { -2, 99, 0, -743, 2, 3, 4 };
    int size = sizeof ints / sizeof *ints;
 
    qsort(ints, size, sizeof(int), compare_ints);
 
    for (i = 0; i < size; i++) {
        printf("%d ", ints[i]);
    }
 
    printf("\n");
 
    return EXIT_SUCCESS;
}

Output:

-743 -2 0 2 3 4 99

[modifica] Vedi anche

cerca una matrice per un elemento di tipo non specificato
Original:
searches an array for an element of unspecified type
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(funzione) [edit]