Re: [Boost-users] How to use Boost Regex Partial Match

Subject: Re: [Boost-users] How to use Boost Regex Partial Match
From: John Maddock (john_at_[hidden])
Date: 2009-04-15 08:06:00

> Given this code.  I expect to get this output from the corresponding 
> input:
>
> Input: FOO  Output: Match
> Input: FOOBAR, Output: Match
> Input: BAR, Output: No Match
>
> But why it gives "No Match" for input FOOBAR?

You - possibly -  have the regex and the string the wrong way around.

You are trying to match the regex "FOO" against the string "FOOBAR" and 
regex_match will only succeed if the *whole of the string matches the 
regex*, with the flag match_partial set then it will also return true if 
*the whole of the string matches a prefix of the regular expression*.

If you really wanted to match all of the regex against a prefix of the 
string (a more common situation) then use regex_search with match_continuous 
set.

And of course, if you want to find an occurance of a regex somewhere within 
the string then set no flags.

HTH, John.