is_file

add a note User Contributed Notes

tatarynowicz at gmail dot com
18-Oct-2006 10:35


An easy way not to have to choose between hard-coding full paths and using relative paths is either via this line:



<?php

// in the bootstrap file

define('DIR_ROOT', dirname(__FILE__));

// in other files, prefix paths with the constant

require(DIR_ROOT . '/relative/to/bootstrap.php');

?>



or if you have to use a relative path:



<?php

require(dirname(__FILE__) . '/relative/to/this_file.php');

?>



This way all your paths will be absolute, yet you can move the application anywhere in the filesystem.



BTW, each successive call to dirname takes you one step up in the directory tree.



<?php

echo __FILE__;

// /www/site.com/public/index.php

echo dirname(__FILE__);

// /www/site.com/public

echo dirname(dirname(__FILE__));

// /www/site.com

?>

SimonCharest at gmail dot com
09-Aug-2006 01:39


In rlh's example, "$ext=explode('.',$document);" is only good if you consider that the filename only possesses a single dot (".") and that it is right before the extension. You should get the last dot's position with the strRPos() function instead.



Another note : some files might not even have an extension (i.e.: mostly under Linux/Unix).

Emin Sadykhov (azdg_nospam at azdg dot com)
12-Dec-2005 09:57


File operations such as is_file (also is_dir, opendir, readdir) work slower with Absolute paths - processing time is increase in 2-3 times. 



Current rule is actual only for PHP5 (tested on 5.0.4, 5.1.1, Windows and Linux, 1st and 2nd Apache)



Try to use relative paths in these operators.



Example tested on my machine:

<?php

# note: in the both conditions file really exists!



# WIN XP, PHP4

# processing time: ~ 0.0003 sec.

if(is_file("images/10.jpg")) echo 'file exists';



# processing time: ~ 0.0002 sec. !!!

if(is_file("C:/server/htdocs/mysite/images/10.jpg")) echo 'file exists';



# WIN XP, PHP5

# processing time: ~ 0.0004 sec.

if(is_file("images/10.jpg")) echo 'file exists';



# processing time: ~ 0.0010 sec.

if(is_file("C:/server/htdocs/mysite/images/10.jpg")) echo 'file exists';

?>

Jonathan Shaltz
15-Oct-2005 01:23


Maybe this is a newbie mistake, but note that paths are relative to the filesystem and the location of the script.  This means that MS IIS virtual directories are not available by relative path - use an absolute.

This threw me because virtual directories ARE available for URLs, at least on IIS.

bill fumerola
31-Aug-2005 09:45


be careful, is_file() fails on files larger than your integer storage (2^32 for most).



Warning: is_file(): Stat failed for bigfile (errno=75 - Value too large for defined data type)

punknroll at gmx dot at
11-Aug-2005 11:11


is_file returns false if you don't have the permissions for the file or the directory (eg.: you are web34 and the directory belongs to root)!

09-Mar-2005 01:02


### Symbolic links are resolved ###



If you pass a symlink (unix symbolic link) as parameter, is_file will resolve the symlink and will give information about the refered file. For example:



  touch file

  ln -s file link

  echo '<? if (is_file("link")) echo "y\n"; ?>' | php -q



will print "y".



is_dir resolves symlinks too.

ludvig dot ericson at gmail dot com
26-Oct-2004 02:06


I tend to use alot of includes, and I found that the is_file is based on the script executed, not ran.

if you request /foo.php and foo.php looks like this:

<?php

include('foobar/bar.php');

?>

and bar.php looks like this:

<?php

echo (is_file('foo/bar.txt'));

?>



Then PHP (on win32, php 5.x) would look for /foo/bar.txt and not /foobar/foo/bar.txt.

you would have to rewrite the is_file statement for that, or change working directory.

Noting this since I sat with the problem for some time,



cheers, Toxik.

rehfeld.us
04-Sep-2004 06:04


regarding rlh at d8acom dot com method,



It is incorrect. Well, it works but you are not guaranteed the file extension using that method.



for example :   filename.inc.php



your method will tell you the ext is "inc", but it is in fact "php"



heres a way that will work properly.



<?php



$dh = opendir($dir);



while (false !== ($document = readdir($dh))) {

    $pos = strrpos($document, '.');

    if (false !== $pos && strlen($document) > $pos + 1) {

        $ext = substr($document, $pos + 1);

    }

}



?>

rlh at d8acom dot com
12-Feb-2003 09:17


I do a lot of file parsing and have found the following technique extremely useful:



while (false !== ($document = readdir($my_dir))) 

{

    $ext=explode('.',$document);

    if($document != '.' && $document != '..' && $ext[1])

    {

                       'Do something to file...'

              }

}



It gets around the fact that, when working on website pages, the html files are read as directories when downloaded. It also allows you to extend the usefulness of the above method by adding the ability to determine file types e.g.



if($document != '.' && $document != '..' && $ext[1]=='htm')

or

if($document != '.' && $document != '..' && $ext[1]=='doc')

andreas dot stagl at fits dot at
28-Mar-2002 03:34


if you're running apache as a service on a win32 machine, an you try to determinate if a file on an other pc in your network exists - ex.: is_file('//servername/share/dir1/dir2/file.txt') - you may return false when you're running the service as LocalSystem. To avoid this, you have to start the Apache-Service as a 'registered' domain user.

quietust at ircN dot org
14-Dec-2001 12:20


In PHP 4.1.0 under win32, this seems to print out a warning message if the file does not exist (using error_reporting = E_ALL & ~E_NOTICE).

amraam at ao dot net
12-Mar-2000 10:56


It seems that is_file doesn't return true for a file that is 0 bytes.  Perhaps it is something with the file system.  I am using IIS 3.0 on an NT4 box.  I worked around it using !is_dir($filename) but that seems a clunky way to do it.

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