PHP array_is_list: Check if an Array is a List with Examples

You need the array_is_list function to know if an array works as a list or not in PHP.

What is the array_is_list in PHP

PHP array_is_list checks if array keys start from 0 and go up by 1.

Here is the syntax:

array_is_list(array $array): bool

This function takes one array and returns true or false.

It looks at keys and checks if they start at 0. Then it checks if the next key goes up by 1. It repeats this check for all keys in the array.

Here is a quick example:

$list = ["red", "blue", "green"];
var_dump(array_is_list($list)); // bool(true)

The result is true because keys start at 0 and each next key adds 1.

The Difference Between the array_is_list and is_array

The is_array function only checks if a value is an array. The array_is_list function checks if an array has order like a list.

Here is a table that shows key differences:

Examples of array_is_list in PHP

Simple List Array:

$fruits = ["apple", "banana", "grape"];
echo array_is_list($fruits) ? "true" : "false";// true

This code shows true because array keys go 0,1,2 without any gap or change. Hence, the array works as a list in PHP code.

Array with Custom Keys:

$fruits = [1 => "apple", 2 => "banana", 3 => "grape"];
echo array_is_list($fruits) ? "true" : "false"; //false

This code shows false because array keys start from 1 instead of 0. Hence, the array does not work as a list in PHP.

Mixed Keys Array:

$data = [0 => "one", 2 => "two", 3 => "three"];
echo array_is_list($data) ? "true" : "false"; // false

This code shows false because keys break at index 1. PHP expects order with no missing steps. Hence, the function detects it is not a list.

Nested List Array:

$list = [[10, 20], [30, 40]];
echo array_is_list($list) ? "true" : "false"; // true

This code shows true because top-level keys go 0 then 1. The function does not check inner keys, so it returns true.

Wrapping Up

In this article, you learned what array_is_list does and how it works with keys. You also saw how it differs from is_array and how to use it.

Here is a quick recap:

• array_is_list checks keys in order from 0 to n.
• is_array checks only if value is an array.
• Use examples to test list or non-list arrays in your PHP code.

FAQs

$array1 = ["a", "b", "c"];
var_dump(array_is_list($array1)); // true

$array2 = [1 => "x", 2 => "y"];
var_dump(array_is_list($array2)); // false

$data = ["apple", "orange", "banana"];
if (array_is_list($data)) {
    echo "This is a list";
} else {
    echo "This is not a list";
}

$test = ["one", "two", "three"];
var_dump(is_array($test));        // true
var_dump(array_is_list($test));   // true

$assoc = ["a" => 1, "b" => 2];
var_dump(is_array($assoc));       // true
var_dump(array_is_list($assoc));  // false

Similar Reads