[英]What regex would find out if file url has certain extension
My valid urls could look more or less like this我的有效网址可能看起来或多或少像这样
http://someurl.com/some/path/file.pdf
or
http://someurl.com/some/path/file.pdf?param=value
or
http://someurl.com/some/path/file.pdf?param=value&second=val
where the file extension could be .pdf, or some other extension like .jpg or .psd, or nothing at all.其中文件扩展名可以是 .pdf,或其他一些扩展名,如 .jpg 或 .psd,或者什么都没有。
I have the url stored without the someurl.com portion, so it's the some/path/file.pdf
part of the url我存储的 url 没有 someurl.com 部分,所以它是 url 的some/path/file.pdf
部分
How can I use regex to know the file extension if it is present?如果存在文件扩展名,我如何使用正则表达式知道它? Is regex the right tool for this?正则表达式是正确的工具吗?
I would use parse_url()
and pathinfo()
.我会使用parse_url()
和pathinfo()
。 These are the most correct functions for the job.这些是工作中最正确的功能。
$url = 'http://someurl.com/some/path/file.pdf?param=value';
$path = parse_url($url, PHP_URL_PATH);
$ext = pathinfo($path, PATHINFO_EXTENSION);
var_dump($ext); // string(3) "pdf"
See is on CodePad.org .请参阅 CodePad.org 。
You could use regex, but it will be more difficult to follow.您可以使用正则表达式,但会更难以遵循。
You would probably need to do a HTTP HEAD request.您可能需要执行 HTTP HEAD 请求。 Regex would work for sure, but you're not guaranteed to catch all cases.正则表达式肯定会起作用,但不能保证您能捕获所有情况。
For example:例如:
http://someurl.com/some/path/file might a be a text file without extension (like on most *nix systems) and the regex would fail to provide the file extension. http://someurl.com/some/path/file可能是一个没有扩展名的文本文件(就像在大多数 *nix 系统上一样)并且正则表达式将无法提供文件扩展名。
Don't need regex, we can just use parse_url
.不需要正则表达式,我们可以只使用parse_url
。
$url = parse_url('http://example.com/path/to/file.php?param=value');
$extension = substr($url['path'], strrpos($url['path'], '.') + 1);
echo $extension; // outputs "php"
http://php.net/parse-url http://php.net/parse-url
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