isset function of PHP

Introduction: This is isset function of PHP detailed page, introduced and php,php, isset isset function of PHP related knowledge, skills, experience, and some PHP source code and so on.

class= ' pingjiaf ' frameborder= ' 0 ' src= ' http://biancheng.dnbcw.info/pingjia.php?id=347709 ' scrolling= ' no ' >

Isset

(PHP 4, PHP 5)

Isset―determine If a variable is set and was not NULL

Checks whether the value of the parameter has been set and is not NULL.

Description

BOOL Isset (mixed $var [, mixed $ ...]

Determine if a variable is set and is not NULL.

If A variable have been unset with unset (), it'll no longer be set. Isset () would return FALSE if testing a variable that have been set to NULL. Also Note that a null byte ("\") is not equivalent to the PHP null constant.

Checks whether the value of the parameter has been set and is not NULL.

If the argument is called unset () and is not set, then it will not be set later. If the parameter is set to NULL, calling Isset () returns false. And the null byte is not the same as the null constant value in PHP.

If multiple parameters is supplied then Isset () would return TRUE if all of the parameters is set. Evaluation goes from the left to the right and stops as soon as a unset variable is encountered.

If you want multiple arguments called isset () to return true, only these functions are set. The function checks all parameters from left to right, and has encountered no set or end of parameter set.

Parameters

var the variable to be checked. The parameter being checked.

... Another variable ... Additional parameters.

Return Values

Returns TRUE if Var exists and has value other than NULL, FALSE otherwise.

If the parameter exists or is not NULL returns TRUE, the other returns false.

Love EE focus on Java Michael Jackson Video station JSON online tool

Http://biancheng.dnbcw.info/php/347709.html Pageno:3

