# dio_truncate

(PHP 4 >= 4.2.0, PHP 5 < 5.1.0)

dio_truncate — Truncates file descriptor fd to offset bytes

### 说明

dio_truncate ( resource `$fd` , int `$offset` ) : bool

dio_truncate() truncates a file to at most `offset` bytes in size.

If the file previously was larger than this size, the extra data is lost. If the file previously was shorter, it is unspecified whether the file is left unchanged or is extended. In the latter case the extended part reads as zero bytes.

### 参数

`fd`

  The file descriptor returned by dio_open().

`offset`

  The offset in bytes.

### 返回值

成功时返回 `TRUE`， 或者在失败时返回 `FALSE`。

### 注释

> Note: 此函数未在 Windows 平台下实现。