REGEX：匹配字符串的开头OPTIONALLY

Question

Im building a regex to match the word combo W7 . Not W73 or NW7 or 2W7 .

So far I have

^w7{1}\b

which works perfectly. However, I have a problem.

I also need to have //W7 (with 2 forward slashs) also match. So if W7 or //W7 are entered they should match

Any ideas?

Thanks!

Answer 1

Just add an optional // at the start.

^(//)?w7\b

You may need to escape them.

^(\/\/)?w7\b

Answer 2

You could just add an optional group to your regex

^(?://)?W7\b

Remember to use a non- / delimiter (it's tidier than escaping those slashes).

If you want the subject string to only ever contain //W7 or W7 then an alternative (full pattern) would be:

~^(?://)?W7$~D

Answer 3

What about ^(//)?W7 ? the question mark indicates one or zero occurrences .