ArrayAccess::offsetExists

(PHP 5 >= 5.0.0)

ArrayAccess::offsetExists — Whether a offset exists

Description

abstract public boolean ArrayAccess::offsetExists ( mixed $offset )

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 boolean if non-boolean was returned.

Examples

Example #1 ArrayAccess::offsetExists() example

 <?php
class obj implements arrayaccess {
    public function offsetSet($offset, $value) {
        var_dump(__METHOD__);
    }
    public function offsetExists($var) {
        var_dump(__METHOD__);
        if ($var == "foobar") {
            return true;
        }
        return false;
    }
    public function offsetUnset($var) {
        var_dump(__METHOD__);
    }
    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)