# CachingIterator::offsetExists

(PHP 5 >= 5.2.0, PHP 7, PHP 8)

CachingIterator::offsetExists — The offsetExists purpose

### 说明

public CachingIterator::offsetExists(string `$key`): bool
警告

本函数还未编写文档，仅有参数列表。

### 参数

`key`

  The index being checked.

### 返回值

Returns `true` if an entry referenced by the offset exists, `false` otherwise.

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