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Name

Synopsis

#include <stdlib.h>

void qsort(void *base, size_t nel, size_t width, int (*compar) (const void *, const void *));

MT-Level

Safe

Description

base points to the element at the base of the table. nel is the number of elements in the table. width specifies the size of each element in bytes. compar is the name of the comparison function, which is called with two arguments that point to the elements being compared. The function must return an integer less than, equal to, or greater than zero to indicate if the first argument is to be considered less than, equal to, or greater than the second argument.

The contents of the table are sorted in ascending order according to the user supplied comparison function.

Examples

The following program sorts a simple array:

static  int intcompare(int *i, int *j)
{
        if (*i > *j)
                return (1);
        if (*i < *j)
                return (-1);
        return (0);
}

main()
{
        int a[10];
        int i;

        a[0] = 9;
        a[1] = 8;
        a[2] = 7;
        a[3] = 6;
        a[4] = 5;
        a[5] = 4;
        a[6] = 3;
        a[7] = 2;
        a[8] = 1;
        a[9] = 0;


        qsort((char *) a, 10, sizeof(int), intcompare);

        for (i=0; i<10; i++) printf(" %d",a[i]);
        printf("\n");
}

See Also

Notes

The relative order in the output of two items that compare as equal is unpredictable.

Table of Contents

• Name
• Synopsis
• MT-Level
• Description
• Examples
• See Also
• Notes