# PHP array_key_exists() Function

PHP Array Reference

## Example

Check if the key "Volvo" exists in an array:

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

## Definition and Usage

The 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.

Tip: Remember that if you skip the key when you specify an array, an integer key is generated, starting at 0 and increases by 1 for each value. (See example 2)

## Syntax

array_key_exists(key,array)

Parameter | Description
--- | ---
key | Required. Specifies the key
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 an array:

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

## Example 2

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

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

PHP Array Reference

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