Re: [Boost-users] problem with regex library

From: John Maddock (john_at_[hidden])
Date: 2006-06-12 12:37:05

Renjie Zhao wrote:
>> After downloading boost_1_33_1, I succeeded in building regex lib
>> with both VC8 and GCC 3.4.2(mingw special)
>>
>> 1st:
>> The following code, which is compiled ok using VC8 (cl
>> a.cpp/I"F:\boost_1_33_1" /EHsc), gives out wrong answer.
>> Well I think the answer is wrong. Do I misunderstand the regular
>> expression? It says"no match" while it is supposed to match twice.
>> 01234 and 56972.
>> If I changes the regex expr to ".*", the code functions well and
>> gives out: The (0) match is:01234abcd56972

>> What is the problem?

You're doing two things completely wrong:

1) regex_match will find one match only if it is a match against the *whole 
of the supplied string*.  To find a match against a sub-set of the supplied 
string use regex_search.
2) The match_results structure contains matches for *marked 
sub-expressions*, only one match is found with regex_search/regex_match.  To 
find multiple matches you iterate through them with regex_iterator or 
regex_token_iterator.

>> 2nd:
>> I got a lot of error messages when I tried to compile the same piece
>> of code with GCC 3.4.2 (mingw-special) under windows 2003
>> and GCC 4.1.0-3 (shipped with Fedora Core 5) under Linux.
>> The previous work using Boost::regex is to build the lib, under
>> windows and linux, the work is done with no error.
>>
>> ------------------error message under
>> windows:------------------------- F:\projects> g++ a.cpp
>> -I"F:\boost_1_33_1" -o a.exe

You haven't supplied a regex lib to link against.  Consult your gcc manual 
for that one.

John.