Regex: Match 'Hello' but not 'Hello world'
 

Hi all,

Is it possible to 'look ahead' with regex?

For example, say I want to match 'hello':

e.g.
>I want to say hello to you - match

but not when it was followed by a specific word, say 'world':

e.g.
>hello, good morning - match
>My output is hello world - don't match
>hello and goodbye - match

My hazy recollection is that this is not possible to look ahead with a single line of regex - do I remember correctly?

Thanks in advance...

Ah, solved it myself:

hello(?! world)

New regex (for me) in Perl 5...