@ emmanuel del grande
You don't need to break when you return...
function bool($var) {
switch (strtolower($var)) {
case ("true"): return true;
case ("false"): return false;
default: die("whatever you want it to tell");
}
}
is_bool
(PHP 4, PHP 5)
is_bool — 変数が boolean であるかを調べる
説明
bool is_bool
( mixed $var
)
指定した変数が boolean であるかどうかを調べます。
パラメータ
- var
-
評価する変数。
返り値
var が boolean である場合に TRUE 、それ以外の場合に FALSE を返します。
例
Example#1 is_bool() の例
<?php
$a = false;
$b = 0;
// $a は boolean なので、これは true です
if (is_bool($a)) {
echo "Yes, this is a boolean";
}
// $b は boolean ではないので、これは true ではありません
if (is_bool($b)) {
echo "Yes, this is a boolean";
}
?>
is_bool
bb at kingdom dot cjb dot net
27-Jun-2007 06:57
27-Jun-2007 06:57
kevin at metalaxe dot com
05-Jun-2007 05:32
05-Jun-2007 05:32
@ emanueledelgrande at email dot it
http://us.php.net/manual/en/language.types.type-juggling.php
(bool) or (boolean) is allowed for type casting a variable. No function like intval, etc but the functionality exists.
emanueledelgrande at email dot it
23-May-2007 01:12
23-May-2007 01:12
I think there's a hole in the PHP typecasting methods:
you have the (int) function, the (float) function and the (string) function, but no function to force a string variable into the boolean type.
It's obvious that forcing unconditionally the type of variables into arrays and objects is inappropriate, but boolean type is the most basic one for each programming language, that's why I guessed that a (bool) function already existed.
Moreover, with the increasing trend of RSS data streaming, the parsing of an XML string into an object often requires to typecast as boolean values the content of XML tags, normally returned as string by the object method get_content().
I wrote the following function, which also uses a "native PHP style" error message:
<?php
// strings tyecasting as boolean values:
function bool($var) {
switch (strtolower($var)) {
case ("true"):
return true;
break;
case ("false"):
return false;
break;
default:
die("<br />\n<b>Warning:</b> Invalid argument supplied for ".__FUNCTION__." function in <b>".__FILE__."</b> on line <b>".__LINE__."</b>: the argument can contain only 'true' or 'false' values as a string.<br />\n");
}
}
?>
Here it is a small example:
<?php
$xmlResponse = "<?xml version=\"1.0\" encoding=\"utf-8\"?>";
$xmlResponse .= "<Result>";
$xmlResponse .= "<AuthError>false</AuthError>";
$xmlResponse .= "<TransferStatus>true</TransferStatus>";
$xmlResponse .= "</Result>";
if (! $responseDoc = domxml_open_mem($xmlResponse, DOMXML_LOAD_PARSING, $XmlParsingError)) {
echo "Error while parsing the XML string:<br />".print_r($XmlParsingError, TRUE);
} else {
$ResultNode = $responseDoc->get_elements_by_tagname('Result');
$AuthError = $ResultNode[0]->get_elements_by_tagname('AuthError');
$auth_error = bool($AuthError[0]->get_content());
$TransferStatus = $ResultNode[0]->get_elements_by_tagname('TransferStatus');
$transfer_status = bool($TransferStatus[0]->get_content());
if (! $auth_error) { echo "Auth OK<br />"; } else { echo "Auth error<br />"; }
if ($transfer_status) { echo "Transfer OK<br />"; } else { echo "Transfer error<br />"; }
}
?>
It would be useful this function to be implemented in the core of PHP5.
21-Apr-2006 08:12
Small caveat to rh's post: back in PHP 3, "0" would be considered non-empty (i.e., empty would return false), even though (bool) on "0" would also evaluate to false; thus, they would not be complete opposites for someone using PHP 3.
rh at richardhoward dot net
23-May-2005 03:17
23-May-2005 03:17
punkpuke is wrong here; what he means to say is that empty($x) is the opposite of (bool)$x. is_bool($x) returns true where $x === false.