Regex - ignore when exists a certain prefix

Question

I want to match any number after the letter v.

So,

• v: 123 matches 123;
• v 123 matches 123;
• v123 matches 123.

But i want to ignore any match when there's any letter behind v.

Like xv: 123 must not match anything.

I'm working with this pattern:

/v[\s\pP]*(\d+)/

but it doesn't ignore situations when somethingbehindv: 123.

Answer 1

An alternative solution would be to use a negative look-behind assertion. This is an extended regular expression and may not supported in whatever language or platform you're using. It would look something like this:

/(?<!\S)v[\s\pP]*(\d+)/

Which basically prevents the pattern from matching if any non-whitespace character(s) (\S) precede the v. You can tweak this, of course, if other characters should be disallowed.

Answer 2

Use a word boundary \b to fix your problem:

/\bv[\s\pP]*(\d+)/