![]() ![]() What’s the difference between these variable testing functions? is_null() is_null ( mixed$var ) : bool Code language: PHP ( php )įinds whether the given variable is NULL. Evaluation goes from left to right and stops as soon as an unset variable is encountered. If multiple parameters are supplied then isset() will return TRUE only if all of the parameters are set. Also note that a null character ( “\0”) is not equivalent to the PHP NULL constant. isset() will return FALSE if testing a variable that has been set to NULL. If a variable has been unset with unset(), it will no longer be set. isset() isset ( mixed$var ) : bool Code language: PHP ( php )ĭetermine if a variable is set and is not NULL. ![]() empty() does not generate a warning if the variable does not exist. A variable is considered empty if it does not exist or if its value equals FALSE. empty() empty ( mixed$var ) : bool Code language: PHP ( php )ĭetermine whether a variable is considered to be empty. We’ll go over why that’s important later in the article.īefore I discuss the difference and show a few examples, here are the descriptions for empty(), isset(), and is_null() from the php.net manual. ![]() empty() and isset() are language constructs, while is_null() is a standard function. Built-in Variable Testing ToolsĪll three of these functions are built into PHP, so they should always be available for your use when writing code. Three of these functions that are easy to mix up are isset(), empty(), and is_null(). There are a variety of functions made to test the state and value of variables, including ones that can tell you if there is anything available to use at all. When I looked into it, it turns out that I was using the wrong function to test for a variable in PHP. This is one of those PD problems, where I wrote some code that stopped functioning. I’ll be honest: most of the posts that I write are either because I’ve solved a problem for a client, or because I solved a problem that Past-david created. ![]()
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