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27 sty 2017 · You can use php variable handling function is_null(mixed $var) which returns TRUE if var is null, otherwise FALSE. <?php $foo = NULL; $bar = 'NULL'; var_dump(is_null($foo), is_null($bar)); ?> OUTPUT. bool(true) bool(false)
The is_null () function checks whether a variable is NULL or not. This function returns true (1) if the variable is NULL, otherwise it returns false/nothing.
9 sty 2024 · In this article, we will explore several ways to check if a variable is NULL in PHP, outlining the steps, code examples, performance considerations, and discussing the pros and cons of each method.
Definition and Usage. The IsNull () function checks whether an expression contains Null (no data). This function returns a Boolean value. TRUE (-1) indicates that the expression is a Null value, and FALSE (0) indicates that the expression is not a Null value. Syntax. IsNull (expression) Parameter Values. Technical Details. More Examples. Example.
30 sty 2019 · Determine if a variable is set and is not NULL. If a variable has been unset with unset (), it will no longer be set. isset () will return FALSE if testing a variable that has been set to NULL. Also note that a null character (“\0”) is not equivalent to the PHP NULL constant.
A second look into the PHP specs tells that is_null() checks whether a value is null or not. So, you may pass any VALUE to it, eg. the result of a function. isset() on the other hand is supposed to check for a VARIABLE's existence, which makes it a language construct rather than a function.
This MSAccess tutorial explains how to use the Access IsNull function with syntax and examples. The Microsoft Access IsNull function returns TRUE if the expression is a null value. Otherwise, it returns FALSE.
