How to Check a Value Exist at Certain Index in an Array in PHP?

Given an array and index, the task is to check whether a value exists or not at a certain index in an array in PHP.

Below are the approaches to check if a value exists at a certain index or not in an array in PHP:

Using isset() Function

The isset() function determines if a variable is set and is not null. It can be used to check if an index exists in an array.

Example: This example shows the use of the above-explained approach.

<?php

function checkValExist($arr, $index) {
    return isset($arr[$index]);
}

// Driver code
$arr = [1, 2, 3, 4, 5];
$index = 3;

if (checkValExist($arr, $index)) {
    echo "Value at index $index exists and is " 
        . $arr[$index];
} else {
    echo "No value exists at index $index.";
}

?>

Value at index 3 exists and is 4

Explanation:

• isset($array[$index]) checks if the index exists in the array and the value is not null.
• If the index exists, the function returns true; otherwise, it returns false.

Using array_key_exists() Function

The array_key_exists() function checks if the specified key or index exists in the array.

Example: This example shows the use of the above-explained approach.

<?php

function checkValExist($arr, $index) {
    return array_key_exists($index, $arr);
}

// Driver code
$arr = [1, 2, 3, 4, 5];
$index = 3;

if (checkValExist($arr, $index)) {
    echo "Value at index $index exists and is: " 
        . $arr[$index];
} else {
    echo "No value exists at index $index.";
}

?>

Value at index 3 exists and is: 4

Explanation:

• array_key_exists($index, $array) checks if the specified index exists in the array.
• If the index exists, the function returns true; otherwise, it returns false.

Using key_exists() Function - Alias of array_key_exists() Function

The key_exists() function is an alias of array_key_exists() and works similarly.

Example: This example shows the use of the above-explained approach.

<?php

function checkValExist($arr, $index) {
    return key_exists($index, $arr);
}

// Driver code
$arr = [1, 2, 3, 4, 5];
$index = 3;

if (checkValExist($arr, $index)) {
    echo "Value at index $index exists and is: " 
        . $arr[$index];
} else {
    echo "No value exists at index $index.";
}

?>

Value at index 3 exists and is: 4

Explanation:

• key_exists($index, $array) checks if the specified index exists in the array.
• If the index exists, the function returns true; otherwise, it returns false.

Using ArrayObject Class

The ArrayObject class allows objects to work as arrays. It has a method called offsetExists which can be used to check if an index exists.

Example: This example shows the use of the above-explained approach.

<?php

function checkValExist($arr, $index) {
    $arrayObject = new ArrayObject($arr);
    return $arrayObject->offsetExists($index);
}

// Driver code
$arr = [1, 2, 3, 4, 5];
$index = 3;

if (checkValExist($arr, $index)) {
    echo "Value at index $index exists and is: " 
        . $arr[$index];
} else {
    echo "No value exists at index $index.";
}

?>

Value at index 3 exists and is: 4