How to get a file's extension in PHP?

This is a question you can read everywhere on the web with various answers:

$ext = end(explode('.', $filename));
$ext = substr(strrchr($filename, '.'), 1);
$ext = substr($filename, strrpos($filename, '.') + 1);
$ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $filename);

$exts = split("[/\\.]", $filename);
$n    = count($exts)-1;
$ext  = $exts[$n];

etc.

However, there is always "the best way" and it should be on Stack Overflow.

People from other scripting languages always think theirs is better because they have a built-in function to do that and not PHP (I am looking at Pythonistas right now :-)).

In fact, it does exist, but few people know it. Meet pathinfo():

$ext = pathinfo($filename, PATHINFO_EXTENSION);

This is fast and built-in. pathinfo() can give you other information, such as canonical path, depending on the constant you pass to it.

Remember that if you want to be able to deal with non ASCII characters, you need to set the locale first. E.G:

setlocale(LC_ALL,'en_US.UTF-8');

Also, note this doesn't take into consideration the file content or mime-type, you only get the extension. But it's what you asked for.

Lastly, note that this works only for a file path, not a URL resources path, which is covered using PARSE_URL.

Enjoy

pathinfo()

$path_info = pathinfo('/foo/bar/baz.bill');

echo $path_info['extension']; // "bill"

Example URL: http://example.com/myfolder/sympony.mp3?a=1&b=2#XYZ

A) Don't use suggested unsafe PATHINFO:

pathinfo($url)['dirname']   🡺 'http://example.com/myfolder'
pathinfo($url)['basename']  🡺 'sympony.mp3?a=1&b=2#XYZ'         // <------- BAD !!
pathinfo($url)['extension'] 🡺 'mp3?a=1&b=2#XYZ'                 // <------- BAD !!
pathinfo($url)['filename']  🡺 'sympony'

B) Use PARSE_URL:

parse_url($url)['scheme']   🡺 'http'
parse_url($url)['host']     🡺 'example.com'
parse_url($url)['path']     🡺 '/myfolder/sympony.mp3'
parse_url($url)['query']    🡺 'aa=1&bb=2'
parse_url($url)['fragment'] 🡺 'XYZ'

BONUS: View all native PHP examples

There is also SplFileInfo:

$file = new SplFileInfo($path);
$ext  = $file->getExtension();

Often you can write better code if you pass such an object around instead of a string. Your code is more speaking then. Since PHP 5.4 this is a one-liner:

$ext  = (new SplFileInfo($path))->getExtension();

Do it faster!

In other words, if you only work with a filename, please stop using pathinfo.

I mean, sure if you have a full pathname, pathinfo makes sense because it's smarter than just finding dots: the path can contain dots and filename itself may have none. So in this case, considering an input string like d:/some.thing/myfile, pathinfo and other fully equipped methods are a good choice.

But if all you have is a filename, with no path, it's simply pointless to make the system work a lot more than it needs to. And this can give you a 10x speed boost.

Here's a quick speed test:

/*   387 ns */ function method1($s) {return preg_replace("/.*\./","",$s);} // edge case problem
/*   769 ns */ function method2($s) {preg_match("/\.([^\.]+)$/",$s,$a);return $a[1];}
/*    67 ns */ function method3($s) {$n = strrpos($s,"."); if($n===false) return "";return substr($s,$n+1);}
/*   175 ns */ function method4($s) {$a = explode(".",$s);$n = count($a); if($n==1) return "";return $a[$n-1];}
/*   731 ns */ function method5($s) {return pathinfo($s, PATHINFO_EXTENSION);}
/*   732 ns */ function method6($s) {return (new SplFileInfo($s))->getExtension();}

//  All measured on Linux; it will be vastly different on Windows

Those nanosecond values will obviously differ on each system, but they give a clear picture about proportions. SplFileInfo and pathinfo are great fellas, but for this kind of job it's simply not worth it to wake them up. For the same reason, explode() is considerably faster than regex. Very simple tools tend to beat more sophisticated ones.

Conclusion

This seems to be the Way of the Samurai:

function fileExtension($name) {
    $n = strrpos($name, '.');
    return ($n === false) ? '' : substr($name, $n+1);
}

Remember this is for simple filenames only. If you have paths involved, stick to pathinfo or deal with the dirname separately.

E-satis's response is the correct way to determine the file extension.

Alternatively, instead of relying on a files extension, you could use the fileinfo to determine the files MIME type.

Here's a simplified example of processing an image uploaded by a user:

// Code assumes necessary extensions are installed and a successful file upload has already occurred

// Create a FileInfo object
$finfo = new FileInfo(null, '/path/to/magic/file');

// Determine the MIME type of the uploaded file
switch ($finfo->file($_FILES['image']['tmp_name'], FILEINFO_MIME)) {        
    case 'image/jpg':
        $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
    break;

    case 'image/png':
        $im = imagecreatefrompng($_FILES['image']['tmp_name']);
    break;

    case 'image/gif':
        $im = imagecreatefromgif($_FILES['image']['tmp_name']);
    break;
}

As long as it does not contain a path you can also use:

array_pop(explode('.', $fname))

Where $fname is a name of the file, for example: my_picture.jpg. And the outcome would be: jpg

1) If you are using (PHP 5 >= 5.3.6) you can use SplFileInfo::getExtension — Gets the file extension

Example code

<?php

$info = new SplFileInfo('test.png');
var_dump($info->getExtension());

$info = new SplFileInfo('test.tar.gz');
var_dump($info->getExtension());

?>

This will output

string(3) "png"
string(2) "gz"

2) Another way of getting the extension if you are using (PHP 4 >= 4.0.3, PHP 5) is pathinfo

Example code

<?php

$ext = pathinfo('test.png', PATHINFO_EXTENSION);
var_dump($ext);

$ext = pathinfo('test.tar.gz', PATHINFO_EXTENSION);
var_dump($ext);

?>

This will output

string(3) "png"
string(2) "gz"

// EDIT: removed a bracket

Sometimes it's useful to not to use pathinfo($path, PATHINFO_EXTENSION). For example:

$path = '/path/to/file.tar.gz';

echo ltrim(strstr($path, '.'), '.'); // tar.gz
echo pathinfo($path, PATHINFO_EXTENSION); // gz

Also note that pathinfo fails to handle some non-ASCII characters (usually it just suppresses them from the output). In extensions that usually isn't a problem, but it doesn't hurt to be aware of that caveat.

Sorry... "Short Question; But NOT Short Answer"

Example 1 for PATH

$path = "/home/ali/public_html/wp-content/themes/chicken/css/base.min.css";
$name = pathinfo($path, PATHINFO_FILENAME);
$ext  = pathinfo($path, PATHINFO_EXTENSION);
printf('<hr> Name: %s <br> Extension: %s', $name, $ext);

Example 2 for URL

$url = "//www.example.com/dir/file.bak.php?Something+is+wrong=hello";
$url = parse_url($url);
$name = pathinfo($url['path'], PATHINFO_FILENAME);
$ext  = pathinfo($url['path'], PATHINFO_EXTENSION);
printf('<hr> Name: %s <br> Extension: %s', $name, $ext);

Output of example 1:

Name: base.min
Extension: css

Output of example 2:

Name: file.bak
Extension: php

References

1. https://www.php.net/manual/en/function.pathinfo.php

2. https://www.php.net/manual/en/function.realpath.php

3. https://www.php.net/manual/en/function.parse-url.php

The simplest way to get file extension in PHP is to use PHP's built-in function pathinfo.

$file_ext = pathinfo('your_file_name_here', PATHINFO_EXTENSION);
echo ($file_ext); // The output should be the extension of the file e.g., png, gif, or html

You can try also this (it works on PHP 5.* and 7):

$info = new SplFileInfo('test.zip');
echo $info->getExtension(); // ----- Output -----> zip

Tip: it returns an empty string if the file doesn't have an extension

Here is an example. Suppose $filename is "example.txt",

$ext = substr($filename, strrpos($filename, '.', -1), strlen($filename));

So $ext will be ".txt".

pathinfo is an array. We can check directory name, file name, extension, etc.:

$path_parts = pathinfo('test.png');

echo $path_parts['extension'], "\n";
echo $path_parts['dirname'], "\n";
echo $path_parts['basename'], "\n";
echo $path_parts['filename'], "\n";

substr($path, strrpos($path, '.') + 1);

A quick fix would be something like this.

// Exploding the file based on the . operator
$file_ext = explode('.', $filename);

// Count taken (if more than one . exist; files like abc.fff.2013.pdf
$file_ext_count = count($file_ext);

// Minus 1 to make the offset correct
$cnt = $file_ext_count - 1;

// The variable will have a value pdf as per the sample file name mentioned above.
$file_extension = $file_ext[$cnt];

You can try also this:

 pathinfo(basename($_FILES["fileToUpload"]["name"]), PATHINFO_EXTENSION)

I found that the pathinfo() and SplFileInfo solutions works well for standard files on the local file system, but you can run into difficulties if you're working with remote files as URLs for valid images may have a # (fragment identifiers) and/or ? (query parameters) at the end of the URL, which both those solutions will (incorrect) treat as part of the file extension.

I found this was a reliable way to use pathinfo() on a URL after first parsing it to strip out the unnecessary clutter after the file extension:

$url_components = parse_url($url); // First parse the URL
$url_path = $url_components['path']; // Then get the path component
$ext = pathinfo($url_path, PATHINFO_EXTENSION); // Then use pathinfo()

Use substr($path, strrpos($path,'.')+1);. It is the fastest method of all compares.

@Kurt Zhong already answered.

Let's check the comparative result here: https://eval.in/661574

IMO, this is the best way if you have filenames like name.name.name.ext (ugly, but it sometimes happens):

$ext     = explode('.', $filename); // Explode the string
$my_ext  = end($ext); // Get the last entry of the array

echo $my_ext;

ltrim(strstr($file_url, '.'), '.')

> this is the best way if you have filenames like name.name.name.ext (ugly, but it sometimes happens

This will work

$ext = pathinfo($filename, PATHINFO_EXTENSION);

You can get all file extensions in a particular folder and do operations with a specific file extension:

<?php
    $files = glob("abc/*.*"); // abc is the folder all files inside folder
    //print_r($files);
    //echo count($files);
    for($i=0; $i<count($files); $i++):
         $extension = pathinfo($files[$i], PATHINFO_EXTENSION);
         $ext[] = $extension;
         // Do operation for particular extension type
         if($extension=='html'){
             // Do operation
         }
    endfor;
    print_r($ext);
?>

$ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $fileName);

preg_replace approach we using regular expression search and replace. In preg_replace function first parameter is pattern to the search, second parameter $1 is a reference to whatever is matched by the first (.*) and third parameter is file name.

Another way, we can also use strrpos to find the position of the last occurrence of a ‘.’ in a file name and increment that position by 1 so that it will explode string from (.)

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

If you are looking for speed (such as in a router), you probably don't want to tokenize everything. Many other answers will fail with /root/my.folder/my.css

ltrim(strrchr($PATH, '.'),'.');

Although the "best way" is debatable, I believe this is the best way for a few reasons:

function getExt($path)
{
	$basename = basename($path);
	return substr($basename, strlen(explode('.', $basename)[0]) + 1);
}

1. It works with multiple parts to an extension, eg tar.gz
2. Short and efficient code
3. It works with both a filename and a complete path

Actually, I was looking for that.

<?php

$url = 'http://example.com/myfolder/sympony.mp3?a=1&b=2#XYZ';
$tmp = @parse_url($url)['path'];
$ext = pathinfo($tmp, PATHINFO_EXTENSION);

var_dump($ext);

I tried one simple solution it might help to someone else to get just filename from the URL which having get parameters

<?php

$path = "URL will be here";
echo basename(parse_url($path)['path']);

?>

Thanks

In one line:

pathinfo(parse_url($url,PHP_URL_PATH),PATHINFO_EXTENSION);

Use

str_replace('.', '', strrchr($file_name, '.'))

for a quick extension retrieval (if you know for sure your file name has one).