PHP checks if the specified key name exists in the array of functions array_key_exists ()

Instance

Check to see if the key name "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 to see if the specified key name exists in an array, returns true if the key name exists, or False if the key name does not exist.

Tip: Keep in mind that if you omit the key name when you specify an array, an integer key name that starts at 0 and increments by 1 is generated. (see Example 2)

Grammar

Array_key_exists (Key,array)

Parameters	Describe
Key	Necessary. Specifies the key name.
Array	Necessary. Specifies the array.

Technical details

return value:	Returns TRUE if the key name exists, or FALSE if the key name does not exist.
PHP version:	4.0.7+

More examples

Example 1

Check that the key name "Toyota" is present 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 that the integer key name "0" is present in the array:

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

Example 1

<?php $a =array ("a" and "Dog", "b" = "Cat"); if (Array_key_exists ("a", $a)) {echo "Key exists!";} else {echo "key does not exist!";}?>

Output:

Key exists!

Example 2

<?php $a =array ("a" and "Dog", "b" = "Cat"); if (Array_key_exists ("C", $a)) {echo "Key exists!";} else {echo "key does not exist!";}?>

Output:

Key does not exist!

Example 2

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

Output:

Key exists!