PHP Reference
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Quick Reference

The PHP array_key_exists() function checks an array for a specified key, and returns “true” if the key exists and “false” if the key does not exist.

<?php
$a = array('Car 1' => 'Lamborghini', 'Car 2' => 'Ferrari');

if (array_key_exists('Car 3', $a)) {
    echo 'The key exists';
}
else {
    echo 'The key does NOT exist';
}
?>

Note

Arrays count starting from zero NOT one. So item 1 is position [0], item 2 is position [1], and item 3 is position [2] … and so on.

Output

The key does NOT exist

Syntax

array_key_exists(key, array)

PHP Notes:

  • When using PHP, single or double quotation marks are acceptable and work identically to one another; choose whichever you prefer, and stay consistent
  • Arrays count starting from zero NOT one; so item 1 is position [0], item 2 is position [1], and item 3 is position [2] … and so on
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