问题
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.
回答1:
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
回答2:
pathinfo()
$path_info = pathinfo('/foo/bar/baz.bill');
echo $path_info['extension']; // "bill"
回答3:
Example URL: http://example.com/myfolder/sympony.mp3?a=1&b=2#XYZ
For URLs, don't use PATHINFO:
$x = pathinfo($url);
$x['dirname'] 🡺 'http://example.com/myfolder'
$x['basename'] 🡺 'sympony.mp3?a=1&b=2#XYZ' // <------- BAD !!
$x['extension'] 🡺 'mp3?a=1&b=2#XYZ' // <------- BAD !!
$x['filename'] 🡺 'sympony'
Use PARSE_URL instead:
$x = parse_url($url);
$x['scheme'] 🡺 'http'
$x['host'] 🡺 'example.com'
$x['path'] 🡺 '/myfolder/sympony.mp3'
$x['query'] 🡺 'aa=1&bb=2'
$x['fragment']🡺 'XYZ'
Note: hashtags are not available in server-side, only if manually added.
For all native PHP examples, see: Get the full URL in PHP
回答4:
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();
回答5:
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;
}
回答6:
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
回答7:
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
回答8:
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.
回答9:
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
回答10:
You can try also this (it works on PHP 5.* and 7):
$info = new SplFileInfo('test.zip');
echo $info->getExtension(); // ----- Output -----> zip
Tip: it returns an empty string if the file doesn't have an extension
回答11:
substr($path, strrpos($path, '.') + 1);
回答12:
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];
回答13:
Here is an example. Suppose $filename is "example.txt",
$ext = substr($filename, strrpos($filename, '.', -1), strlen($filename));
So $ext will be ".txt".
回答14:
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";
回答15:
This will work
$ext = pathinfo($filename, PATHINFO_EXTENSION);
回答16:
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()
回答17:
You can try also this:
pathinfo(basename($_FILES["fileToUpload"]["name"]), PATHINFO_EXTENSION)
回答18:
Use substr($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
回答19:
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, $ext);
Output of example 1:
Name: base.min
Extension: css
Output of example 2:
Name: file.bak
Extension: php
References
https://www.php.net/manual/en/function.pathinfo.php
https://www.php.net/manual/en/function.realpath.php
https://www.php.net/manual/en/function.parse-url.php
回答20:
If you are looking for speed (such as in a router), you probably don't want to tokenize everything. Many other answers will fail with /root/my.folder/my.css
ltrim(strrchr($PATH, '.'),'.');
回答21:
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);
}
- It works with multiple parts to an extension, eg
tar.gz - Short and efficient code
- It works with both a filename and a complete path
回答22:
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);
?>
回答23:
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);
回答24:
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
$ext_len = count($ext) - 1; // Count the array -1 (because count() starts from 1)
$my_ext = $ext[$ext_len]; // Get the last entry of the array
echo $my_ext;
回答25:
$ext = preg_replace('/^.*\.([^.]+)$/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($fileName, '.') + 1);
回答26:
ltrim(strstr($file_url, '.'), '.')
this is the best way if you have filenames like name.name.name.ext (ugly, but it sometimes happens
回答27:
Use
str_replace('.', '', strrchr($file_name, '.'))
for a quick extension retrieval (if you know for sure your file name has one).
来源：https://stackoverflow.com/questions/173868/how-do-i-get-extract-a-file-extension-in-php