How to check if a key exists in an array in PHP

Use the PHP array_key_exists() function

You can use the PHP array_key_exists() function to test whether a given key or index exists in an array or not. This function returns TRUE on success or FALSE on failure.

Let's take a look at the following example to understand how it actually works:

<?php
$cities = array("France"=>"Paris", "India"=>"Mumbai", "UK"=>"London", "USA"=>"New York");
 
// Testing the key exists in the array or not
if(array_key_exists("France", $cities)){
    echo "The key 'France' is exists in the cities array";
}
?>