How to Use the PHP empty() Function

This easy tutorial will show you how to use the PHP empty() function to check whether a variable can be considered empty and show some code examples.

What Is Empty?

A variable is considered empty in PHP if its value equates to FALSE or the variable does not exist.

This means that the following are considered empty:

• An empty string (“”)
• The number zero (0)
  • In any form (0.0000)
  • Including strings containing only a 0 character (“0”)
• Boolean FALSE
• NULL
• An undeclared variable
• Empty arrays

The empty() function is different from the isset() function. The latter checks only whether a variable is declared and not null.

PHP empty() Function Syntax

The syntax for the empty() function is as follows:

empty(VAR)

Note that:

• VAR should be the variable to be checked for emptiness
• empty() will return a boolean value (TRUE or FALSE)
  • TRUE if the passed VAR is empty
  • FALSE if it is not
• If the variable *VAR has not been declared, no error will be thrown!
  • FALSE will be returned instead

Php empty() Function Examples

$var = NULL;
if(empty($var)) echo $var . ' is empty!\n';

$var = '0';
if(empty($var)) echo $var . ' is empty!\n';

$var = 0;
if(empty($var)) echo $var . ' is empty!\n';

$var = '';
if(empty($var)) echo $var . ' is empty!\n';

$var = "";
if(empty($var)) echo $var . ' is empty!\n';

$var = null;
if(empty($var)) echo $var . ' is empty!\n';

$var = [];
if(empty($var)) echo json_encode($var) . ' is empty!\n'; // The array is JSON encoded so it can be printed

$var = (object)[]; // Creates an empty object
if(empty($var)) echo json_encode($var) . ' is empty!\n'; // The object is JSON encoded so it can be printed

$var = FALSE;
if(empty($var)) echo $var . ' is empty!\n';

Notice that the empty object is not considered empty by isempty()!