In what scenarios would using isset() be more efficient than array_key_exists() for checking the existence of elements in PHP arrays?

When checking for the existence of elements in PHP arrays, using isset() is more efficient than array_key_exists() when you only need to check if a key exists in the array regardless of its value. isset() is a language construct that is faster than array_key_exists() as it directly checks if a variable is set and is not NULL. On the other hand, array_key_exists() checks if a key exists in an array, including keys with NULL values. 

// Using isset() to check the existence of elements in an array
$array = ['key1' => 'value1', 'key2' => null];

if(isset($array['key1'])){
    echo 'Key1 exists in the array';
}

// Output: Key1 exists in the array

Keywords

isset array_key_exists efficiency PHP arrays existence

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