Checks whether an object exists in the storage

# SplObjectStorage::offsetExists

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

SplObjectStorage::offsetExists — Checks whether an object exists in the storage

### 说明

public function SplObjectStorage::offsetExists(object `$object`): bool

Checks whether an object exists in the storage.

> 注意:

> SplObjectStorage::offsetExists() is an alias of SplObjectStorage::contains().

### 参数

`object`

  The object to look for.

### 返回值

Returns `true` if the object exists in the storage, and `false` otherwise.

### 示例

示例 #1 SplObjectStorage::offsetExists() example

    <?php
    $s = new SplObjectStorage;
    $o1 = new stdClass;
    $o2 = new stdClass;

    $s->attach($o1);

    var_dump($s->offsetExists($o1)); // Similar to isset($s[$o1])
    var_dump($s->offsetExists($o2)); // Similar to isset($s[$o2])
    ?>

以上示例的输出类似于：

    bool(true)
    bool(false)

### 参见

- SplObjectStorage::offsetSet() - Associates data to an object in the storage
- SplObjectStorage::offsetGet() - Returns the data associated with an object
- SplObjectStorage::offsetUnset() - Removes an object from the storage

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