A Regular expression to find the letter 'v' followed by any amount of numbers and possibly a dot

I need a regular expression to find something in a string so that it can be removed.

I need to find when there is something like V100, v1, V1.0, or v10.0123, so the letter 'v' upper or lower case, followed by any number of numbers that could possibly have a '.' in it, but it being sandwiched between other characters should not find it.


words v10 - it should find v10
wordsv1 - it should not find v1
v1words -it should not find v1

I'm new to regular expressions, so if you could please explain what each part of the expression means that would be very helpful thanks!
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Bill PrewIT / Software Engineering ConsultantCommented:
I think you could use this to return the matching text you are looking for:


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Here is a great online tool for poking at and learning regex, and it shows a breakdown of each piece of the regular expression.  Take a look and come back with questions you still have.

Bill is almost right.

Try this:

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1. I swapped out \s for \b, because \s is for whitespace (and there's no guarantee that there will be whitespace around the value), while \b is for word boundaries, so it won't find "abcv1def" but it will find "Hello world.v1" and similar instances where you want to ensure you're not matching in the middle of a bigger word.

2. I changed the * to + so it would require at LEAST one number or dot (so "v" alone would not match).

3. I changed the . to a \. because . by itself means "any character" while \. means "the dot character"

4. I changed "v" to "[vV]" to look for upper or lower case V letters. You could also just use the case-insensitive flag on your method, too. Either way would handle the case issue.

Since the dot cannot be after v then try

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Bill PrewIT / Software Engineering ConsultantCommented:
Good on upper and lower V's, I didn't catch that on first read.  And I like the 1 or more better than 0 or more, agreed.  But inside a character list [0-9.] I'm pretty sure there is no need to escape the period.  Sure it works, but not needed...

It's hard to know from the question description if \b or \s makes more sense.  I went more conservative, since it felt like xxxx-v1 should not match, but it depends on authors specific needs.

So I'll land at:


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Bill PrewIT / Software Engineering ConsultantCommented:
Well, we don't know that v.10 is not valid, do we?

then try

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buttonMASTERAuthor Commented:
Hi everyone. Thank you for your answers. I'm currently going through everything to see what works for my use cases.

Well, we don't know that v.10 is not valid, do we?
v.10 would not be valid, thanks for checking.
Bill PrewIT / Software Engineering ConsultantCommented:
Okay, here's an adjusted version of mine, based on discussion here.  And some additional test cases.

Try changing the \s to \b (two of them) in the regex to see the difference, then choose based on your needs.



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buttonMASTERAuthor Commented:
Thank you all for your help.

Bill, you were so helpful with those links and accounting for v1.2.3 was great. gr8gonzo good job for reading the entire question and explaining things. And Rgonzo1971 you answer was correct for what I described in my question, but Bill caught cases I didn't think about.
Bill PrewIT / Software Engineering ConsultantCommented:
Welcome, glad that was helpful.

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Regular Expressions

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