正则表达式在字符串中查找某些URL

Question

I'm not very good at Regex, but I've been working on improving. Right now I'm trying to make a regex expression to match all URLs in a string that follows a certain syntax. Here is my regex code:

@http://api\.ning\.com:80/files/[a-z0-9\*]/[a-z0-9\.]\.[jpg|png|gif|bmp]@i

Here is an example of something I want this to match (but it isn't matching):

http://api.ning.com:80/files/etWx3bZZxVPTI8A3sSd3zoLhhkTmjoCs2IRFnOacPoHzJogudMCze2mB2Fib0Z*R/ScreenShot20131111at4.58.13PM.png?width=375

Answer 1

You need to do two things:

1. Add a + at the end of group of characters [a-z0-9*] and [a-z0-9.]
2. Move the file extensions in parentheses instead of square brackets

The expression would become:

@http://api\.ning\.com:80/files/[a-z0-9\*]+/[a-z0-9\.]+\.(jpg|png|gif|bmp)@i

which can be further simplified to:

@http://api\.ning\.com:80/files/[\w\*]+/[\w\.]+\.(jpg|png|gif|bmp)@

Note that \\w already includes upper-case and lower-case letters as well as numbers. So, you can get rid of the i flag too unless you need it for the file extensions or the base URL.