DrTebi at yahoo dot com is wrong. is_readable() checks whether you can do file_get_contents() or similar calls, no more, no less. If the location given returns a 500 or 403 error, you can still read() that (you'll simply get the error page), but it's still read()able. Using is_readable to check the validity of a URL is simply the wrong function.
is_readable
(PHP 4, PHP 5)
is_readable — Tells whether a file exists and is readable
說明
bool is_readable
( string
$filename
)Tells whether a file exists and is readable.
參數
-
filename -
Path to the file.
回傳值
Returns TRUE if the file or directory specified by
filename exists and is readable, FALSE otherwise.
範例
Example #1 is_readable() example
<?php
$filename = 'test.txt';
if (is_readable($filename)) {
echo 'The file is readable';
} else {
echo 'The file is not readable';
}
?>
錯誤/例外
失敗時拋出E_WARNING警告。
註釋
Keep in mind that PHP may be accessing the file as the user id that the web server runs as (often 'nobody'). Safe mode limitations are not taken into account before PHP 5.1.5.
Note: 本函式的結果會被存入緩衝區。詳情參見 clearstatcache()。
Tip
自 PHP 5.0.0 起本函式也可被某些 URL wrapper 使用。參考Supported Protocols and Wrappers 來看哪些 wrapper 支援 stat() 系列函式的功能。
Note:
The check is done using the real UID/GID instead of the effective one.
This function may return TRUE for directories. Use
is_dir() to distinguish file and directory.
參見
- is_writable() - Tells whether the filename is writable
- file_exists() - Checks whether a file or directory exists
- fgets() - Gets line from file pointer
add a note
User Contributed Notes 4 notes
jo at durchholz dot org ¶
18 years ago
pgl at yoyo dot org ¶
14 years ago
Note that is_readable() will return false for streams, eg, php://stdin.
arikan134 at gmail dot com ¶
8 years ago
is readable recursively. Check all sub directories and files readable
<?php
function is_readable_r($dir) {
if (is_dir($dir)) {
if(is_readable($dir)){
$objects = scandir($dir);
foreach ($objects as $object) {
if ($object != "." && $object != "..") {
if (!is_readable_r($dir."/".$object)) return false;
else continue;
}
}
return true;
}else{
return false;
}
}else if(file_exists($dir)){
return (is_readable($dir));
}
}
?>
