diff options
| author | Giorgos Keramidas <keramida@FreeBSD.org> | 2013-02-25 19:09:13 +0000 |
|---|---|---|
| committer | Giorgos Keramidas <keramida@FreeBSD.org> | 2013-02-25 19:09:13 +0000 |
| commit | f55f4d32fbace7f835ae678c927526edc192bed4 (patch) | |
| tree | 0d0859835d336460ffbe35dad539c83dd6fac8e3 /lib | |
| parent | 3cac94e0752ae180c45def98eb81a6c73e4523cc (diff) | |
MFH r247014, r247050 and r247051.
Add a sample program that shows how a custom comparison function and
qsort(3) can work together to sort an array of integers.
PR: docs/176197
Submitted by: Fernando, fapesteguia at opensistemas.com
Christoph Mallon, christoph.mallon at gmx.de
Approved by: gjb (mentor), remko (mentor)
Notes
svn path=/stable/8/; revision=247276
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/libc/stdlib/qsort.3 | 42 |
1 files changed, 41 insertions, 1 deletions
diff --git a/lib/libc/stdlib/qsort.3 b/lib/libc/stdlib/qsort.3 index 0f7ef7334470..f34d260b7fc9 100644 --- a/lib/libc/stdlib/qsort.3 +++ b/lib/libc/stdlib/qsort.3 @@ -32,7 +32,7 @@ .\" @(#)qsort.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD$ .\" -.Dd September 30, 2003 +.Dd February 20, 2013 .Dt QSORT 3 .Os .Sh NAME @@ -205,6 +205,46 @@ functions return no value. .Pp .Rv -std heapsort mergesort +.Sh EXAMPLES +A sample program that sorts an array of +.Vt int +values in place using +.Fn qsort , +and then prints the sorted array to standard output is: +.Bd -literal +#include <stdio.h> +#include <stdlib.h> + +/* + * Custom comparison function that can compare 'int' values through pointers + * passed by qsort(3). + */ +static int +int_compare(const void *p1, const void *p2) +{ + int left = *(const int *)p1; + int right = *(const int *)p2; + + return ((left > right) - (left < right)); +} + +/* + * Sort an array of 'int' values and print it to standard output. + */ +int +main(void) +{ + int int_array[] = { 4, 5, 9, 3, 0, 1, 7, 2, 8, 6 }; + const size_t array_size = sizeof(int_array) / sizeof(int_array[0]); + size_t k; + + qsort(&int_array, array_size, sizeof(int_array[0]), int_compare); + for (k = 0; k < array_size; k++) + printf(" %d", int_array[k]); + puts(""); + return (EXIT_SUCCESS); +} +.Ed .Sh COMPATIBILITY Previous versions of .Fn qsort |