How to Check Whether a Variable is Empty in PHP?

Given some values of variables, the task is to check whether the variable is empty or not in PHP. An empty variable can refer to a variable that has not been set, a variable that has been explicitly set to an empty value, or a variable that contains a value that is considered empty. In this article, we will explore different approaches to check whether a variable is empty in PHP.

Approach 1: Using empty() Function

The empty() function is a built-in PHP function that checks whether a variable is empty. A variable is considered empty if it does not exist, or if its value is equal to false, 0, “” (an empty string), “0” (a string containing zero), null, or an empty array.

PHP

<?php

$var1 = null;
$var2 = "";
$var3 = 0;
$var4 = "0";
$var5 = false;
$var6 = [];
$var7 = "Hello";

echo "Is variable 1 empty? " . (empty($var1) ? 'true' : 'false') . "\n";
echo "Is variable 2 empty? " . (empty($var2) ? 'true' : 'false') . "\n";
echo "Is variable 3 empty? " . (empty($var3) ? 'true' : 'false') . "\n";
echo "Is variable 4 empty? " . (empty($var4) ? 'true' : 'false') . "\n";
echo "Is variable 5 empty? " . (empty($var5) ? 'true' : 'false') . "\n";
echo "Is variable 6 empty? " . (empty($var6) ? 'true' : 'false') . "\n";
echo "Is variable 7 empty? " . (empty($var7) ? 'true' : 'false');

?>

Output

Is variable 1 empty? true
Is variable 2 empty? true
Is variable 3 empty? true
Is variable 4 empty? true
Is variable 5 empty? true
Is variable 6 empty? true
Is variable 7 empty? false

Explanation:

• The empty() function returns true if the variable is empty and false otherwise.

Approach 2: Using isset() Function

The isset() function is another built-in PHP function that checks whether a variable is set and is not null.

PHP

<?php

$var1 = null;
$var2 = "";
$var3 = 0;
$var4 = "0";
$var5 = false;
$var6 = [];
$var7 = "Hello";

echo "Is variable 1 empty? " . (isset($var1) && $var1 === '' ? 'true' : 'false') . "\n";
echo "Is variable 2 empty? " . (isset($var2) && $var2 === '' ? 'true' : 'false') . "\n";
echo "Is variable 3 empty? " . (isset($var3) && $var3 === 0 ? 'true' : 'false') . "\n";
echo "Is variable 4 empty? " . (isset($var4) && $var4 === '0' ? 'true' : 'false') . "\n";
echo "Is variable 5 empty? " . (isset($var5) && $var5 === false ? 'true' : 'false') . "\n";
echo "Is variable 6 empty? " . (isset($var6) && $var6 === [] ? 'true' : 'false') . "\n";
echo "Is variable 7 empty? " . (isset($var7) && $var7 === '' ? 'true' : 'false');

?>

Output

Is variable 1 empty? false
Is variable 2 empty? true
Is variable 3 empty? true
Is variable 4 empty? true
Is variable 5 empty? true
Is variable 6 empty? true
Is variable 7 empty? false

Explanation:

• The isset() function returns true if the variable is set and is not null. Also, Additional comparisons are used to check for specific empty values like an empty string, zero, or false.