ArrayAccess::offsetExists

(PHP 5, PHP 7, PHP 8)

ArrayAccess::offsetExistsWhether an offset exists

Description

public ArrayAccess::offsetExists(mixed $offset): bool

Whether or not an offset exists.

This method is executed when using isset() or empty() on objects implementing ArrayAccess.

Note:

When using empty() ArrayAccess::offsetGet() will be called and checked if empty only if ArrayAccess::offsetExists() returns true.

Parameters

offset

An offset to check for.

Return Values

Returns true on success or false on failure.

Note:

The return value will be casted to bool if non-boolean was returned.

Examples

Example #1 ArrayAccess::offsetExists() example

<?phpclass obj implements ArrayAccess {    public function offsetSet($offset, $value): void {        var_dump(__METHOD__);    }    public function offsetExists($var): bool {        var_dump(__METHOD__);        if ($var == "foobar") {            return true;        }        return false;    }    public function offsetUnset($var): void {        var_dump(__METHOD__);    }    #[\ReturnTypeWillChange]    public function offsetGet($var) {        var_dump(__METHOD__);        return "value";    }}$obj = new obj;echo "Runs obj::offsetExists()\n";var_dump(isset($obj["foobar"]));echo "\nRuns obj::offsetExists() and obj::offsetGet()\n";var_dump(empty($obj["foobar"]));echo "\nRuns obj::offsetExists(), *not* obj:offsetGet() as there is nothing to get\n";var_dump(empty($obj["foobaz"]));?>

The above example will output something similar to:

Runs obj::offsetExists()
string(17) "obj::offsetExists"
bool(true)

Runs obj::offsetExists() and obj::offsetGet()
string(17) "obj::offsetExists"
string(14) "obj::offsetGet"
bool(false)

Runs obj::offsetExists(), *not* obj:offsetGet() as there is nothing to get
string(17) "obj::offsetExists"
bool(true)