is_writable
(PHP 4, PHP 5)
is_writable — Tells whether the filename is writable
說明
bool is_writable
( string $filename
)
Returns TRUE if the filename exists and is writable. The filename argument may be a directory name allowing you to check if a directory is writable.
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.
參數
- filename
-
The filename being checked.
Return值
Returns TRUE if the filename exists and is writable.
範例
Example#1 is_writable() example
<?php
$filename = 'test.txt';
if (is_writable($filename)) {
echo 'The file is writable';
} else {
echo 'The file is not writable';
}
?>
註釋
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。