Does Ruby regular expression have a not match operator like “!~” in Perl?

Question

I just want to know whether ruby regex has a not match operator just like !~ in perl. I feel it\'s inconvenient to use (?!xxx)or (?

Answer 1

Back in perl, 'foobar' !~ /bar/ was perfectly perlish to test that the string doesn't contain "bar".

In Ruby, particularly with a modern style guide, I think a more explicit solution is more conventional and easy to understand:

input = 'foobar'

do_something unless input.match?(/bar/) 

needs_bar = !input.match?(/bar/)

That said, I think it would be spiffy if there was a .no_match? method.

Answer 2

AFAIK (?!xxx) is supported:

2.1.5 :021 > 'abc1234' =~ /^abc/
 => 0
2.1.5 :022 > 'def1234' =~ /^abc/
 => nil
2.1.5 :023 > 'abc1234' =~ /^(?!abc)/
 => nil
2.1.5 :024 > 'def1234' =~ /^(?!abc)/
 => 0

Answer 3

Yes: !~ works just fine – you probably thought it wouldn’t because it’s missing from the documentation page of Regexp. Nevertheless, it works:

irb(main):001:0> 'x' !~ /x/
=> false
irb(main):002:0> 'x' !~ /y/
=> true