Re: [Boost-users] regex problem: removing two elements in a row?

From: Lynn Allan (l_d_allan_at_[hidden])
Date: 2007-01-25 13:35:58

ooops  ... and thanks for the very prompt help to this regex newbie 
... I'm very much at the "trial and error" state of getting regex 
statements to work.

Would one of the following be the preferred "assignment"?
reg.assign("(\\<and\\>|\\<can\\>|\\<did\\>|\\<the\\>|\\<in\\>|\\<a\\>)");
or
reg.assign("\\<(and|can|did|the|in|a)\\>");

Both seem to work, but perhaps this regex newbie is missing a better 
alternative.

What is the "x modifier"? I looked up the perl explanation, and the 
boost::regex documentation, but that seemed related to formatting the 
statement itself.

Also, thanks for the time and effort you put into boost::regex ... 
development and ongoing support.

"John Maddock" <john_at_[hidden]> wrote in message 
news:008501c740a2$e2dc0c60$f0fc0c52_at_fuji...
> Lynn Allan wrote:
>> I want to use boost::regex 1.33.1 and vc7.1 on a WinXp-Sp2 computer 
>> to
>> remove common words from a file. I'm encountering a problem which
>> seems related to having two of the common words next to each other.
>>
>> std::string test(" in the beginning god created the heavens and the
>> earth ");
>> boost::regex reg;
>> reg.assign("( and | can | did | the | in | a )");
>> test = boost::regex_replace(test, reg, "  ");
>> cout << test << endl;
>>
>> The result is:
>> " the beginning god created  heavens  the earth "
>>
>> Am I doing something wrong or leaving out a step? Seems like the 
>> above
>> ought to work. It catches one of the occurrences of " the " between 
>> "
>> created " and " heavens " but not those immediately after the " in 
>> "
>> or " and ".
>
> Check your whitespace in the expression: the first match is " in ", 
> the
> remaining text then starts "the beginning" which won't match " the " 
> etc
> etc.
>
> Did you mean to turn on the x-modifier?
>
> John.