Question

I’m trying to get a regex that will match:

somefile_1.txt somefile_2.txt somefile_{anything}.txt 

but not match:

somefile_16.txt 

I tried

somefile_[^(16)].txt 

with no luck (it includes even the ’16’ record)

Answer 1

Some regex libraries allow lookahead:

somefile(?!16\.txt$).*?\.txt 

Otherwise, you can still use multiple character classes:

somefile([^1].|1[^6]|.|.{3,})\.txt 

or, to achieve maximum portability:

somefile([^1].|1[^6]|.|....*)\.txt 

[^(16)] means: Match any character but braces, 1, and 6.