get_resource_type()

(PHP 4 >= 4.0.2, PHP 5, PHP 7)

返回资源（resource）类型

描述

此函数返回一个字符串，用于表示传递给它的resource的类型。如果参数不是合法的resource，将产生错误。

Try this to know behavior:

It will be shown as...
[Check Valid Resource]
(bool)$resource => TRUE
get_resource_type($resource) => stream
is_resoruce($resource) => TRUE
[Check Released Resource]
(bool)$resource => TRUE
get_resource_type($resource) => Unknown
is_resoruce($resource) => FALSE
[Check NULL]
(bool)$resource => FALSE
get_resource_type($resource) => FALSE
Warning: get_resource_type() expects parameter 1 to be resource, null given in ... on line 10
is_resoruce($resource) => FALSE

In PHP5 (on Linux), the above example identifies the "file" handler as a 'stream', not 'file'.
This can be particularly worrisome if you're trying to determine the type of stream using this function.
The alternative is to use , which returns an array containing "stream_type (string) - a label describing the underlying implementation of the stream."

Furthermore, this function returns 'stream' on php 4.3 on windows & linux.
You if you want to differentiate between a file resource and other stream resources, as stated before stream_get_meta_data() gives you an array which, on my system, contains the following elements which might suggest a file handle:
[wrapper_type] => plainfile
[stream_type] => STDIO
However I've only compared this to a stream from a url, so I include this only as a suggestion.

This function will generate an error and return NULL instead FALSE in the next example: 

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