Get file extension in PHP

Using pathinfo()

(PHP 4 >= 4.0.3, PHP 5)

$fileName = '/home/documents/my.file.doc';

$fileInfo = pathinfo($fileName);

$fileExtension = $fileInfo['extension'];

echo $fileExtension;

will output:

doc

As you can see fileinfo() offers more information about the file and it works only for the file name (my.file.doc) or for the whole path (/home/documents/my.file.doc):

print_r($fileInfo);

will output:

Array
(
    [dirname] => /home/documents
    [basename] => my.file.doc
    [extension] => doc
    [filename] => my.file
)

Using substr() and strpos()

$path = '/home/documents/my.file.doc';

$fileName = substr($path, strrpos($path, '/') + 1);

$fileExtension = substr($fileName, strrpos($fileName, '.') + 1);

echo $fileExtension;
will output:
doc

Notice: it will give erroneous results if the file does not have an extension (also for linux hidden files starting with a dot)

Using preg_match()

Avoid preg_match() in favor of strpos() if possible because it is faster.

Get directory and file name

$path = '/home/documents/my.file.doc';

preg_match('|^(.*)([^/]+)$|U', $path, $matches);

U modifier = non greedy, see http://php.net/manual/en/reference.pcre.pattern.modifiers.php

print_r($matches);

will output:

Array
(
    [0] => /home/documents/my.file.doc
    [1] => /home/documents/
    [2] => my.file.doc
)

Get file extension

$path = '/home/documents/my.file.doc';

preg_match('|([^\.]+)$|', $path, $matches);

$fileExtension = $matches[1];