Author: kib
Date: Wed Jul 24 06:32:21 2019
New Revision: 350273
URL: https://svnweb.freebsd.org/changeset/base/350273
Log:
MFC r347617 (by bcr), r350091:
Add an example to bsearch.3.
Modified:
stable/11/lib/libc/stdlib/bsearch.3
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/lib/libc/stdlib/bsearch.3
==============================================================================
--- stable/11/lib/libc/stdlib/bsearch.3 Wed Jul 24 06:29:19 2019
(r350272)
+++ stable/11/lib/libc/stdlib/bsearch.3 Wed Jul 24 06:32:21 2019
(r350273)
@@ -32,7 +32,7 @@
.\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94
.\" $FreeBSD$
.\"
-.Dd February 22, 2013
+.Dd July 17, 2019
.Dt BSEARCH 3
.Os
.Sh NAME
@@ -83,6 +83,70 @@ The
function returns a pointer to a matching member of the array, or a null
pointer if no match is found.
If two members compare as equal, which member is matched is unspecified.
+.Sh EXAMPLES
+A sample program that searches people by age in a sorted array:
+.Bd -literal
+#include <assert.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct person {
+ const char *name;
+ int age;
+};
+
+static int
+compare(const void *a, const void *b)
+{
+ const int *age;
+ const struct person *person;
+
+ age = a;
+ person = b;
+
+ return (*age - person->age);
+}
+
+int
+main(void)
+{
+ struct person *friend;
+ int age;
+ /* Sorted array */
+ const struct person friends[] = {
+ { "paul", 22 },
+ { "anne", 25 },
+ { "fred", 25 },
+ { "mary", 27 },
+ { "mark", 35 },
+ { "bill", 50 }
+ };
+ const size_t len = sizeof(friends) / sizeof(friends[0]);
+
+ age = 22;
+ friend = bsearch(&age, friends, len, sizeof(friends[0]), compare);
+ assert(strcmp(friend->name, "paul") == 0);
+ printf("name: %s\enage: %d\en", friend->name, friend->age);
+
+ age = 25;
+ friend = bsearch(&age, friends, len, sizeof(friends[0]), compare);
+
+ /*
+ * For multiple elements with the same key, it is implementation
+ * defined which will be returned
+ */
+ assert(strcmp(friend->name, "fred") == 0 ||
+ strcmp(friend->name, "anne") == 0);
+ printf("name: %s\enage: %d\en", friend->name, friend->age);
+
+ age = 30;
+ friend = bsearch(&age, friends, len, sizeof(friends[0]), compare);
+ assert(friend == NULL);
+ printf("friend aged 30 not found\en");
+}
+.Ed
.Sh SEE ALSO
.Xr db 3 ,
.Xr lsearch 3 ,
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