is_readable
(PHP 4, PHP 5)
is_readable — Tells whether the filename is readable
說明
bool is_readable
( string $filename
)
Tells whether the filename is readable.
參數
- filename
-
Path to the file.
Return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';
}
?>
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List of Supported Protocols/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.