PHP: Check if a variable exists
June 20, 2022 ‐ 1 min read
Referencing a variable that hasn't been set in PHP fails rather silently. You might see a PHP warning like the following:
PHP Warning: Undefined variable $var
To check whether a variable has been set in PHP we use the isset() function, which returns false if the passed variable has not been set.
<?php
if (isset($var) === false)
{
echo 'Variable has not been set';
}