Clarify how strcmp() should be used as the 'compar'

function by providing an example.

man3/qsort.3

@@ -27,6 +27,7 @@
 .\"
 .\" Modified 1993-03-29, David Metcalfe
 .\" Modified 1993-07-24, Rik Faith (faith@cs.unc.edu)
+.\" 2006-01-15, mtk, Added example program.
 .\"
 .TH QSORT 3 2003-11-15 "" "Linux Programmer's Manual"
 .SH NAME
@@ -61,14 +62,49 @@ SVID 3, POSIX, 4.3BSD, ISO 9899
 Library routines suitable for use as the
 .I compar
 argument include
-.BR strcmp (),
+.BR strcmp () 
+(see below),
 .BR alphasort (),
 and
 .BR versionsort ().
 .SH EXAMPLE
-For an example of use, see the example on the
-.BR bsearch (3)
-page.
+For one example of use, see the example under
+.BR bsearch (3).
+
+The following example program sorts the strings given
+in its command-line arguments:
+.sp
+.nf
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <assert.h>
+
+static int
+cmpstringp(const void *p1, const void *p2)
+{
+    /* The arguments to this function are "pointers to
+       pointers to char", but strcmp() arguments are "pointers
+       to char", hence the following cast plus dereference */
+
+    return strcmp(* (char **) p1, * (char **) p2);
+}
+
+int
+main(int argc, char *argv[])
+{
+    int j;
+
+    assert(argc > 1);
+
+    qsort(&argv[1], argc - 1, sizeof(char *), cmpstringp);
+
+    for (j = 1; j < argc; j++)
+        puts(argv[j]);
+    exit(EXIT_SUCCESS);
+}
+.fi
 .SH "SEE ALSO"
 .BR sort (1),
 .BR alphasort (3),