NAME

qsort - sort a table of data

SYNOPSIS

#include <stdlib.h>

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


DESCRIPTION

^[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard.

The qsort() function shall sort an array of nel objects, the initial element of which is pointed to by base. The size of each object, in bytes, is specified by the width argument.

The contents of the array shall be sorted in ascending order according to a comparison function. The compar argument is a pointer to the comparison function, which is called with two arguments that point to the elements being compared. The application shall ensure that the function returns an integer less than, equal to, or greater than 0, if the first argument is considered respectively less than, equal to, or greater than the second. If two members compare as equal, their order in the sorted array is unspecified.

RETURN VALUE

The qsort() function shall not return a value.

ERRORS

No errors are defined.

EXAMPLES

None.

APPLICATION USAGE

The comparison function need not compare every byte, so arbitrary data may be contained in the elements in addition to the values being compared.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

The Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

The DESCRIPTION is updated to avoid use of the term "must" for application requirements.