is_binary
@ 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.
is_bool
(PHP 4, PHP 5)
is_bool — Finds out whether a variable is a boolean
Description
bool is_bool ( mixed $var )Finds whether the given variable is a boolean.
Parameters
- var
The variable being evaluated.
Return Values
Returns TRUE if var is a boolean, FALSE otherwise.
Examples
Example 2523. is_bool() examples
<?php
$a = false;
$b = 0;
// Since $a is a boolean, this is true
if (is_bool($a)) {
echo "Yes, this is a boolean";
}
// Since $b is not a boolean, this is not true
if (is_bool($b)) {
echo "Yes, this is a boolean";
}
?>
See Also
| is_float() |
| is_int() |
| is_string() |
| is_object() |
| is_array() |
add a note
User Contributed Notesis_bool
kevin at metalaxe dot com
05-Jun-2007 08:32
05-Jun-2007 08:32
emanueledelgrande at email dot it
22-May-2007 04:12
22-May-2007 04:12
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 11:12
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
22-May-2005 06:17
22-May-2005 06:17
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.