qsort(3C)						   Standard C Library Functions 						 qsort(3C)

NAME

       qsort - quick sort

SYNOPSIS

       #include <stdlib.h>

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

DESCRIPTION

       The  qsort()  function  is  an implementation of the quick-sort algorithm. It sorts a table of data in place. The contents of the table are
       sorted in ascending order according to the  user-supplied comparison function.

       The base argument points to the element at the base of the table.  The nel argument is the number of elements  in  the  table.	The  width
       argument specifies the size of each element in bytes.  The compar argument 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.

USAGE

       The qsort() function safely allows concurrent access by	multiple threads to disjoint data, such as overlapping subtrees or tables.

EXAMPLES

       Example 1: Program sorts.

       The following program sorts a simple array:

       #include <stdlib.h>
       #include <stdio.h>

       static int
       intcompare(const void *p1, const void *p2)
       {
	   int i = *((int *)p1);
	   int j = *((int *)p2);

	   if (i > j)
	       return(1);
	   if (i < j)
	       return (-1);
	   return(0);
       }

       int
       main()
       {
	   int i;
	   int a[10] = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 };
	   size_t nelems = sizeof (a) / sizeof (int);

	   qsort((void *)a, nelems, sizeof (int), intcompare);

	   for (i = 0; i < nelems; i++) {
	       (void) printf("%d ", a[i]);
	   }

	   (void) printf("
");
	   return(0);
       }

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       sort(1), bsearch(3C), lsearch(3C), string(3C), attributes(5), standards(5)

NOTES

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

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

SunOS 5.10							    6 Dec 2004								 qsort(3C)