PHP和文件路径中的file_exists（）

Question

I have a folder uploads in the root folder. There is another folder A in the root, and contains a PHP file. I have the following code in the PHP file:

$imgpath = '/uploads/' . $filename;
echo '<img src="' . $imgpath . '" />';
echo (file_exists($imgpath))?'true':'false';

It will show the image, so the file exists, but file_exists shows false .

If I change '/uploads/' to '../uploads/' , it will show the image and file_exists shows true . Even if there is no image, file_exists always shows true .

What is the problem?

* Update *

I tried echo dirname(__FILE__); . It shows /....../A , the uploads folder is located at /....../uploads . Moreover, I have another similar PHP file in folder /....../m/A . So I need some kind of universal path. How to get the root path, ie, /....../ ?

I also tried $_SERVER['DOCUMENT_ROOT'] , but the image cannot be shown, although the path is 100% correct.

Answer 1

To avoid problems, it's easiest to use an absolute path with file_exists(). The system root / is not the same as your web root (eg,) /var/www

Try

# /var/www/A/script.php
$imgpath = '/uploads/' . $filename;

# check in /var/www/uploads/filename
if( file_exists(dirname(__FILE__) . '/..' . $imgpath) ) {
    echo '<img src="' . $imgpath . '" />';
}

EDIT for PHP >= 5.3

$path = "/uploads/${filename}";

if (file_exists(sprinf("%s/..%s", __DIR__, $path)) {
  echo "<img src=\"{$path}\">;
}

Answer 2

Starting out with "/" means a relative path on the web, but on file systems that is referencing the folder "uploads" inside the root "/" directory.

Try ./uploads notation or use dirname(__FILE__) .

Answer 3

The reason is that your absolute path in HTML is relative to your website root, but in PHP it is relative to the file-system root. They are not the same.

My website root is http://www.example.com/ but my site is developed on the file-system at /var/www/ So if I was in /var/www/index.php and used the path /uploads/ , in html that would be http://www.example.com/uploads/ but for a file-system that would be /uploads/ . I'm not even in my website directory anymore!