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Digg  is_bool
Finds out whether a variable is a boolean
(PHP 4, PHP 5)
Example 2589. is_bool() examples<?phpCode Examples / Notes » is_bool21-apr-2006 12:12
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
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 $x === false.
emanueledelgrande
I think there's a hole in the PHP typecasting methods: you have the (int) function, the (float) function and the (string) function, but no function to force a string variable into the boolean type. It's obvious that forcing unconditionally the type of variables into arrays and objects is inappropriate, but boolean type is the most basic one for each programming language, that's why I guessed that a (bool) function already existed. Moreover, with the increasing trend of RSS data streaming, the parsing of an XML string into an object often requires to typecast as boolean values the content of XML tags, normally returned as string by the object method get_content(). I wrote the following function, which also uses a "native PHP style" error message: <?php // strings tyecasting as boolean values: function bool($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. bb
@ 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"); } } admin @ ifyouwantblood dotty de
@ emmanuel del grande and kevin at metalaxe dot com also there is settype: http://us.php.net/settype kevin
@ 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. |
Change Language
debug_zval_dump doubleval empty floatval get_defined_vars get_resource_type gettype import_request_variables intval is_array is_binary is_bool is_buffer is_callable is_double is_float is_int is_integer is_long is_null is_numeric is_object is_real is_resource is_scalar is_string is_unicode isset print_r serialize settype strval unserialize unset var_dump var_export |
