PHP isset() function

This function is used to check whether a variable is set with a value or null.

Syntax

isset(variablename);

The variable name is the required field. It returns true if the variable is set with a value and false otherwise.

Example

<?php
    $var1 = 'Hello World';
    $var2;
    if(isset($var1)) {
        echo 'The variable is set a value.<br/>';
    }
    if(isset($var2)) {
        echo 'The variable is set a value.<br/>';
    }
    else{
        echo 'The variable is null.';
    }
?>

Outcome -

The variable is set a value.
The variable is null.

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