How to Use empty() in PHP: Syntax, Examples, and Tips

In PHP, empty() is a function used to check if a variable is empty or not set. It returns true if the variable has a value considered empty like 0, "", null, or false, and false otherwise. Use it to safely test variables without causing errors if they don't exist.

Syntax

The empty() function checks if a variable is empty or not set. It takes one argument: the variable to check.

• Variable: The variable you want to test.
• Returns: true if the variable is empty or not set, false otherwise.

php

empty($variable);

Example

This example shows how empty() returns true for different empty values and false for non-empty values.

php

<?php
$values = ["", 0, 0.0, "0", null, false, [], "hello", 123];
foreach ($values as $value) {
    if (empty($value)) {
        echo "Empty\n";
    } else {
        echo "Not Empty\n";
    }
}
?>

Output

Empty
Empty
Empty
Empty
Empty
Empty
Empty
Not Empty
Not Empty

Common Pitfalls

One common mistake is expecting empty() to only check for null or "". It treats 0, "0", false, and empty arrays as empty too. Also, empty() does not raise an error if the variable is not defined, unlike direct checks.

Wrong way (causes warning if variable not set):

if ($var == false) { /* ... */ }

Right way (safe even if variable not set):

if (empty($var)) { /* ... */ }

Quick Reference

empty() returns true for these values:

• "" (empty string)
• 0 (integer zero)
• 0.0 (float zero)
• "0" (string zero)
• null
• false
• [] (empty array)
• Undefined variables

Key Takeaways

Use empty() to check if a variable is empty or not set without errors.

empty() treats 0, "0", false, null, "", and empty arrays as empty.

It is safer than direct comparisons because it does not warn on undefined variables.

Remember empty() returns a boolean: true if empty, false if not.

Use empty() to simplify checks before using variables in your code.