How to Check if a Key Exists in an Array in PHP

To check if a key exists in an array in PHP, you can use the array_key_exists() function. This function is designed to check if a specific key is present in an array, regardless of the key’s value.

Here’s how you can use array_key_exists():

$array = [
    'name' => 'John',
    'age' => 30,
    'email' => '[email protected]'
];

$keyToCheck = 'age';

if (array_key_exists($keyToCheck, $array)) {
    echo "Key '$keyToCheck' exists in the array.";
} else {
    echo "Key '$keyToCheck' does not exist in the array.";
}

Key Points:#

• Function: array_key_exists($key, $array)
• Parameters:
  • $key — The key you want to check.
  • $array — The array where you want to check the key.
• Returns: true if the key exists, false otherwise.

This function works with both associative arrays (where keys are strings) and indexed arrays (where keys are integers). For indexed arrays, you can check for integer keys in the same way.

Example with Indexed Array:#

$array = [10, 20, 30];

$keyToCheck = 1; // checking for the index 1

if (array_key_exists($keyToCheck, $array)) {
    echo "Index $keyToCheck exists in the array.";
} else {
    echo "Index $keyToCheck does not exist in the array.";
}

Note:#

• For checking the existence of values, you would use in_array() instead.
• If you are using PHP 7.4 or higher, array_key_exists() works efficiently with both numeric and string keys.