get_resource_type
(PHP 4 >= 4.0.2, PHP 5, PHP 7)
get_resource_type — 返回资源（resource）类型
描述
$handle
)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。
<?php
$c = mysql_connect ();
echo get_resource_type ( $c ). "\n" ;
// 打印：mysql link
$fp = fopen ( "foo" , "w" );
echo get_resource_type ( $fp ). "\n" ;
// 打印：file
$doc = new_xmldoc ( "1.0" );
echo get_resource_type ( $doc -> doc ). "\n" ;
// 打印：domxml document
?> 用户评论:
[#1] CertaiN [2014-01-17 05:04:06]
Try this to know behavior:
<?php
function resource_test($resource, $name) {
echo
'[' . $name. ']',
PHP_EOL,
'(bool)$resource => ',
$resource ? 'TRUE' : 'FALSE',
PHP_EOL,
'get_resource_type($resource) => ',
get_resource_type($resource) ?: 'FALSE',
PHP_EOL,
'is_resoruce($resource) => ',
is_resource($resource) ? 'TRUE' : 'FALSE',
PHP_EOL,
PHP_EOL
;
}
$resource = tmpfile();
resource_test($resource, 'Check Valid Resource');
fclose($resource);
resource_test($resource, 'Check Released Resource');
$resource = null;
resource_test($resource, 'Check NULL');
?>
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
[#2] avp200681 at gmail dot com [2011-06-13 03:11:13]
This function will generate an error and return NULL instead FALSE in the next example:
<?php
$var = 3;
var_dump(get_resource_type($var));
?>
[#3] hessodreamy at gmail dot com [2007-05-29 04:07:13]
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.
[#4] jdhawk _at_ gmail [2005-10-05 13:18:10]
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
<?php stream_get_meta_data() ?>
, which returns an array containing "stream_type (string) - a label describing the underlying implementation of the stream."