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I am updating some code that I didn’t write and part of it is a regex as follows:
\[url(?:\s*)\]www\.(.*?)\[/url(?:\s*)\]
I understand that .*? does a non-greedy match of everything in the second register.
What does ?:\s* in the first and third registers do?
Update: As requested, language is C# on .NET 3.5
The syntax
(?:)is a way of putting parentheses around a subexpression without separately extracting that part of the string.The author wanted to match the
(.*?)part in the middle, and didn’t want the spaces at the beginning or the end from getting in the way. Now you can use\1or$1(or whatever the appropriate method is in your particular language) to refer to the domain name, instead of the first chunk of spaces at the beginning of the string