Re: [boost] Regex Problem?

From: John Maddock (john_at_[hidden])
Date: 2003-12-10 06:41:20

> According to my understanding of regular expressions, all three should
> report the same things.  But the Non Greedy example produces mangled
output.
> I can't even understand how that output is being generated.
>
> Is this a Boost bug, or have I done something wrong?

You've done something wrong: in the non greedy version:

(.*?) : (.*?) , (.*?)

The final repeat ($3) matches a zero length string right before the "776"
part (because it's non-greedy remember).

So when generating the new string from "$1" it copies:

Everything from the start of the string to the start of the match : ""
Then $1 : "City 15"
Everything from the end of the match to the end of the  text : "776"

To produce "City 15776" in all.

You can suppress copying of unmatched sections with the match_flag:
format_no_copy, but then you would loose the final 776 part altogether.

John.