The is_null() function is a built-in function in PHP that checks whether a variable is null or not. Null is a special value that represents the absence of a value.


The syntax of the is_null() function is as follows:

bool is_null(mixed $var)

The function takes a single parameter, $var, which is the variable to be checked for being null. The function returns true if the variable is null, and false otherwise.

Example Usage

Here is an example of how to use the is_null() function in PHP:

$var1 = null;
$var2 = "hello";
echo is_null($var1) . "\n";  // output: 1 (true)
echo is_null($var2) . "\n";  // output: (false)

In this example, we define two variables: $var1 is null, and $var2 is a string. We then use the is_null() function to check whether each variable is null. The output shows that $var1 is null (true), while $var2 is not null (false).


The is_null() function is a useful tool for checking whether a variable is null in PHP. It can be used to ensure that a variable has a value before attempting to use it, or to handle null and non-null variables in a particular way. By using this function, developers can ensure that their code is working with the correct data types and avoid errors that may occur when working with mixed data types.

Practice Your Knowledge

What does the is_null function in PHP do?

Quiz Time: Test Your Skills!

Ready to challenge what you've learned? Dive into our interactive quizzes for a deeper understanding and a fun way to reinforce your knowledge.

Do you find this helpful?