svn commit: r347951 - stable/12/lib/libc/stdlib

[Konstantin Belousov]

On Sat, May 18, 2019 at 03:15:08AM +0000, Benedict Reuschling wrote:
> Author: bcr (doc committer)
> Date: Sat May 18 03:15:07 2019
> New Revision: 347951
> URL: https://svnweb.freebsd.org/changeset/base/347951
> 
> Log:
>   MFC r347617:
>   Add small EXAMPLE section to bsearch.3.
>   
>   Submitted by:		    fernape (via Phabricator)
>   Reviewed by:		    bcr, jilles, dab
>   Approved by:		    bcr (man pages), jilles (src)
>   Differential Revision:	    https://reviews.freebsd.org/D19902
> 
> Modified:
>   stable/12/lib/libc/stdlib/bsearch.3
> Directory Properties:
>   stable/12/   (props changed)
> 
> Modified: stable/12/lib/libc/stdlib/bsearch.3
> ==============================================================================
> --- stable/12/lib/libc/stdlib/bsearch.3	Sat May 18 02:02:14 2019	(r347950)
> +++ stable/12/lib/libc/stdlib/bsearch.3	Sat May 18 03:15:07 2019	(r347951)
> @@ -32,7 +32,7 @@
>  .\"     @(#)bsearch.3	8.3 (Berkeley) 4/19/94
>  .\" $FreeBSD$
>  .\"
> -.Dd February 22, 2013
> +.Dd May 15, 2019
>  .Dt BSEARCH 3
>  .Os
>  .Sh NAME
> @@ -83,6 +83,61 @@ 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 {
> +	char name[5];
> +	int age;
> +};
> +
> +int
> +compare(const void *key, const void *array_member)
> +{
> +	int age = (intptr_t) key;
> +	struct person person = *(struct person *) array_member;
These two lines contain at least three style(9) bugs, and at least one
warning at higher warning level.

> +
> +	return (age - person.age);
> +}
> +
> +int
> +main()
Why use K&R definition ?

> +{
> +	struct person *friend;
> +
> +	/* Sorted array */
> +	struct person friends[6] = {
> +		{ "paul", 22 },
> +		{ "anne", 25 },
> +		{ "fred", 25 },
> +		{ "mary", 27 },
> +		{ "mark", 35 },
> +		{ "bill", 50 }
> +	};
> +
> +	size_t array_size = sizeof(friends) / sizeof(struct person);
Since you used const elsewere, why did not you used it there ?

> +
> +	friend = bsearch((void *)22, &friends, array_size, sizeof(struct person), compare);
Taking address of an array is weird.
Line is too long.

> +	assert(strcmp(friend->name, "paul") == 0);
> +	printf("name: %s\enage: %d\en", friend->name, friend->age);
> +
> +	friend = bsearch((void *)25, &friends, array_size, sizeof(struct person), compare);
> +	assert(strcmp(friend->name, "fred") == 0 || strcmp(friend->name, "anne") == 0);
> +	printf("name: %s\enage: %d\en", friend->name, friend->age);
> +
> +	friend = bsearch((void *)30, &friends, array_size, sizeof(struct person), compare);
> +	assert(friend == NULL);
> +	printf("friend aged 30 not found\en");
> +
> +	return (EXIT_SUCCESS);
> +}
> +.Ed
>  .Sh SEE ALSO
>  .Xr db 3 ,
>  .Xr lsearch 3 ,