PHP array_key_exists() function

Example

Check whether the key "Volvo" exists in the array:

<?php$a=array("Volvo"=>"XC90","BMW"=>"X5");if (array_key_exists("Volvo",$a)) { echo "Key exists!"; }else { echo "Key does not exist!"; }?>

Definition and usage

The array_key_exists() function checks whether the specified key exists in an array. It returns true if the key exists and false if the key does not exist.

Tip: Remember that if you omit the keys when specifying an array, integer keys will be generated starting at 0 and increasing by 1. (See Example 2)

grammar

 array_key_exists( key,array )

parameter	describe
key	Required. Specifies the key name.
array	Required. Specifies an array.

technical details

Return value:	Returns TRUE if the key exists, and FALSE if the key does not exist.
PHP version:	4.0.7+

More examples

Example 1

Check if the key "Toyota" exists in the array:

<?php$a=array("Volvo"=>"XC90","BMW"=>"X5");if (key_exists("Toyota",$a)) { echo "Key exists!"; }else { echo "Key does not exist!"; }?>

Example 2

Check if the integer key "0" exists in the array:

<?php$a=array("Volvo","BMW");if (array_key_exists(0,$a)) { echo "Key exists!"; }else { echo "Key does not exist!"; }?>