PHP array_key_exists() Function
Topic: PHP Array ReferencePrev|Next
Description
The array_key_exists() function checks if the given key or index exists in the array.
The following table summarizes the technical details of this function.
| Return Value: | Returns TRUE on success or FALSE on failure. |
|---|---|
| Version: | PHP 4.0.7+ |
Syntax
The basic syntax of the array_key_exists() function is given with:
The following example shows the array_key_exists() function in action.
Example
Run this code »<?php
// Sample array
$lang = array("en"=>"English", "fr"=>"French", "ar"=>"Arabic");
// Test if key exists in the array
if(array_key_exists("fr", $lang)){
echo "Key exists!";
} else{
echo "Key does not exist!";
}
?>Parameters
The array_key_exists() function accepts the following parameters.
| Parameter | Description |
|---|---|
| key | Required. Specifies the key to check. |
| array | Required. Specifies the target array in which key will be checked. |
Note: The array_key_exists() function will search for the keys in the first dimension only. Nested keys in multidimensional arrays will not be searched.
Tip: In PHP 4.0.6 and earlier version, the array_key_exists() function was called key_exists(). The key_exists() is still used as an alias for the array_key_exists() function.
More Examples
Here're some more examples showing how array_key_exists() function basically works:
This function can also be used to check whether an index exist in an array, like this:
Example
Run this code »<?php
// Sample array
$cities = array("London", "Paris", "New York");
// Test if key exists in the array
if(array_key_exists(0, $cities)){
echo "Key exists!";
} else{
echo "Key does not exist!";
}
?>Tip: In an indexed or numeric array, the indexes are automatically assigned (start with 0 and increases by 1 for each value), and the values can be any data type.
