PHP Variable Handling empty() Function

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The PHP Variable Handling empty() function is used to check that a variable is empty or not. A variable is considered empty if it is either nonexistent or has a value of false. The empty() function does not generate a warning if there is no variable.

It can change textual or integer values to decimal numbers (floats). It is useful when you want to confirm that your data is in float format, mainly if performing calculations or working with numerical data.

Syntax

Below is the syntax of the PHP Variable Handling empty() function −

bool empty ( mixed $var )

Parameters

This function accepts $var parameter which is the variable that will be examined. If the variable is not present, no warning is given. So empty() is basically !isset($var) || $var == false's concise equivalent.

Return Value

This function returns −

• true − if the variable is empty

• false − if variable exists or has a non-empty or non-zero value

The following values evaluates to empty −

• integer − if value is 0 then empty() returns true. For any other value returns false.

• float − if value is 0.0 then empty() returns true. For any other value returns false.

• string − if string value is "0" and null ("") then empty() returns true. For any other value returns false (even "0.0").

• array − if value is empty array() then boolval() returns true. For any other value returns false.

• NULL − empty() always returns false when variable is NULL.

• Boolean − if boolean variable is FALSE then empty() returns true.

PHP Version

First introduced in core PHP 4, the empty() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

First we will show you the basic example of the PHP Variable Handling empty() function to checks if a string is empty.

<?php
$str = "";
if (empty($str)) {
    echo "The string is empty.";
} else {
    echo "The string is not empty.";
}
?>

Output

Here is the outcome of the following code −

The string is empty.

Example 2

This program uses empty() function to check that if a number is zero.

<?php
$num = 0;
if (empty($num)) {
    echo "The number is zero or empty.";
} else {
    echo "The number is not zero.";
}
?> 

Output

This will generate the below output −

The number is zero or empty.

Example 3

This program performs checks if an array is empty with the help of the empty() function. Here we are using false value so it will return FALSE.

<?php
$arr = [1, 2, 3];
if (empty($arr)) {
    echo "The array is empty.";
} else {
    echo "The array is not empty.";
}
?> 

Output

This will create the below output −

The array is not empty.

Example 4

In the following example, we are using the empty() function to checks if multiple form fields are empty and shows appropriate error messages.

<?php
// Mention form data
$formData = [
    'name' => '',
    'email' => 'test@example.com',
    'age' => 0,
    'message' => null,
];

// Validate each field
$errors = [];

if (empty($formData['name'])) {
    $errors[] = "Name is required.";
}

if (empty($formData['email'])) {
    $errors[] = "Email is necessary.";
}

if (empty($formData['age'])) {
    $errors[] = "Age can not be empty or zero.";
}

if (empty($formData['message'])) {
    $errors[] = "Message can not be empty.";
}

// Display errors or success message
if (!empty($errors)) {
    echo "Errors found:<br>";
    foreach ($errors as $error) {
        echo "- $error<br>";
    }
} else {
    echo "Form has been submitted successfully!";
}
?> 

Output

Following is the output of the above code −

Errors found:
- Name is required.
- Age can not be empty or zero.
- Message can not be empty.