fclose()

(PHP 4, PHP 5, PHP 7)

关闭一个已打开的文件指针

说明

将$handle指向的文件关闭。

参数

文件指针必须有效，并且是通过fopen()或fsockopen()成功打开的。

返回值

成功时返回TRUE，或者在失败时返回FALSE。

范例

一个简单fclose()例子

参见

• fopen() 打开文件或者 URL
• fsockopen() 打开一个网络连接或者一个Unix套接字连接

It is a GOOD_THING to check the return value from fclose(), as some operating systems only flush file output on close, and can, therefore, return an error from fclose(). You can catch severe data-eating errors by doing this. 
I learned this the hard way.

In case you have some trouble to properly disconnect some client streams opened with stream_socket_server / stream_select you should give a try to stream_socket_shutdown. 

Generally, it's always a good idea to close a file when you're done with it. It's very easy for something to go wrong and corrupt a file that hasn't been closed properly. If you're concerned about efficiency, the overhead is negligible.

if you want to daysychain a filehandle through some functions and each function is allowed to close th file you might look in a following function first, if the handle is still valid.
Opening a file, there often will be used a code like
if (!$fh = fopen($filename, $mode)) return false;
But if you possably have closed the file and you want to check that, a smililar statement would not work.
DOES NOT WORK:  if (!$fh) end_of_chain();
use beter: if (is_resource($fh))  end_of_chain();

It is very important to make sure you clear any incoming packets out of the incoming buffer using fread() or some equivalent. Although you can call fclose() the socket does not actually shut down until the inbound packets have been cleared. This can lead to some confusion.

In response to kumar mcmillan 'gotcha' note below, we get a different result on a W2K machine:

output:
$file_pointer is resource = false

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