Array key exists() Function in PHP

In this tutorial, we’ll take a closer look at PHP Func Array Key Exists / array_key_exists() function and how you can use it to improve your PHP code.

If you’re a PHP developer, you might be familiar with the array_key_exists() function. This handy function allows you to check if a specified key exists in an array or not.

What is PHP array_key_exists() function?

The Func Array Key Exists OR array_key_exists() function is a built-in PHP function that checks if a specified key exists in an array or not. It takes two parameters: the first parameter is the key that you want to check for, and the second parameter is the array you want to search.

The function returns true if the key exists in the array; otherwise, it returns false if the key does not exist in the array.

When a key is used within an array, this function can be used to detect if the value that corresponds to that key exists within the array before accessing its value.

Moreover, it is possible to use this method for determining whether a given key exists in an array, regardless of what value it has.

The use of an array also contributes to the use of control structures within a program, since these structures often determine how a program flows based on whether a specific key exists or not in the array in Func Array Key Exists.


array_key_exists(key, array)

Parameter Values

keyThis is required. This specifies the key that will be used
arrayThis is required. This method specifies an array of elements

Using the array_key_exists() function

The following code will check to see if the key “FirstName” is present in an array:


<?php $array = array( "FirstName"=>"Mark", "LastName"=>"Zuckerberg", "Age"=>38, "Gender"=>"M", ); if (array_key_exists("FirstName", $array)) { echo "First name exists!"; } else { echo "First name does not exist!"; } ?>

The following code checks for a “DOB” key in the array:


<?php $array = array( "FirstName"=>"Mark", "LastName"=>"Zuckerberg", "Age"=>38, "Gender"=>"M", ); if (array_key_exists("DOB", $array)) { echo "Date of birth exists!"; } else { echo "Date of birth does not exist!"; } ?>
This code checks if there is an array containing the integer key “2” in the following order:


<?php $array = array("Sunflower", "Tulip", "Rose"); if (array_key_exists(2,$array)) { echo "Key exists!"; } else { echo "Key does not exist!"; } ?>

Example Explanation:

We have an array with three elements: Sunflower, Tulip, and Rose. We want to check if there exists an element at the index 2 of the array. So, we use the PHP function Func Array Key Exists / array_key_exists(), which takes two arguments: the key we want to check and the array we want to check it in.

In this case, we check if the key 2 exists in the array $array. Since the element at index 2 is “Rose”, which is present in the array, the condition is true, and the output will be “Key exists!”.

Therefore, if we run this code, we will see the message “Key exists!” displayed on the screen.

Array key exists Benefits

The array_key_exists() function in PHP is a useful tool when working with arrays. Here are some benefits of using array_key_exists():

I. Key Existence Check:

The primary purpose of array_key_exists() is to check whether a specified key exists in an array. This is crucial when you want to ensure that a key is present before attempting to access its associated value. This prevents potential errors and avoids undefined index notices.


$myArray = array('name' => 'John', 'age' => 25, 'city' => 'New York'); if (array_key_exists('age', $myArray)) { // Key 'age' exists in $myArray $age = $myArray['age']; echo "Age: $age"; } else { echo "Key 'age' does not exist"; }

II. Avoiding Errors:

Without checking for key existence, attempting to access a non-existent key directly may lead to errors, especially when error reporting is set to display notices. array_key_exists() helps in avoiding these errors and ensures a smoother execution of your code.

III. Conditional Logic:

The function is often used in conditional statements to execute specific code based on whether a key exists or not. This is particularly useful for handling different scenarios depending on the availability of certain data in an array.

if (array_key_exists('email', $userDetails)) {
// Process email-related functionality
} else {
// Handle the case when 'email' key is not present

IV. Readable Code:

The use of array_key_exists() enhances the readability of your code by explicitly stating the intention of checking for a key’s existence. This makes the code more understandable for both the original coder and other developers who may review or collaborate on the project.

V. Compatibility:

array_key_exists() is available in all PHP versions, making it a reliable and widely-supported function. It provides a consistent way to check for the existence of keys across different PHP environments.

VI. Alternative to isset():

While isset() can also be used to check if a key exists in an array, array_key_exists() is more suitable for this purpose. isset() can give false positives for keys with null values, while array_key_exists() only checks the existence of the key, regardless of its value.


$myArray = array('name' => null);

// Incorrect usage with isset()
if (isset($myArray['name'])) {
// This block will be executed, but it's misleading

// Correct usage with array_key_exists()
if (array_key_exists('name', $myArray)) {
// This block won't be executed because 'name' exists but has a null value


The Func Array Key Exists / array_key_exists() function is a powerful tool for PHP developers. It allows you to check if a specified key exists in an array before trying to access it, which can help you avoid undefined index errors and improve your code. By using this function, you can create more robust and reliable PHP applications.

You can help others learn about the power and flexible nature of PHP Array Function by sharing our article on social media below. This will enable them to create dynamic and interactive web applications.

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