in_array() / array_key_exists()
function
in_array() checks if a value exists; array_key_exists() checks if a key exists in an array.
Syntax
in_array(mixed $needle, array $haystack, bool $strict = false): bool
Example
php
<?php
$fruits = ['apple','banana','cherry'];
var_dump(in_array('banana', $fruits)); // true
var_dump(in_array('grape', $fruits)); // false
var_dump(in_array('1', [1,2,3], true)); // false (strict)
$user = ['name'=>'Alice','age'=>28];
var_dump(array_key_exists('name', $user)); // true