Re: [Boost-users] RegExp - Callback function

From: Golan Trevize (G.Trevize_at_[hidden])
Date: 2007-10-27 12:21:41

Hello.

Thanks you very much.

It was only stupid example, I need it for something complete diferent. And I couldn't find the right solution. 
I know, how do this in PHP, where it's easy... In C++ it was for me problem...

Thanks once more.

> ------------ Pùvodní zpráva ------------
> Od: John Maddock <john_at_[hidden]>
> Pøedmìt: Re: [Boost-users] RegExp - Callback function
> Datum: 27.10.2007 17:37:59
> ----------------------------------------
> Golan Trevize wrote:
> > I need use regexp. The idea is that I use 'replace', it find some
> > text like in expression and this will be an input for function...
> > then in function something happen and output of the function replace
> > in text the input of the function...
> >
> > For example I've got text "Solution: 5 and 4". Regular expression is
> > "[0-9]" And the function is "add5"
> > int add5(int input){return input+5}
> > And the output of this function replace the number with number+5...
> > And in the end text will be: "Solution: 10 and 9"
> >
> > In C++ with Boost? I don't know how can I do it...
> 
> You need to iterate over the matches and replace each occurance with your 
> new text, off the top of my head something like:
> 
> extern std::string text_to_search;
> std::string result_text;
> boost::regex r("[[:digit:]]+");
> 
> boost::sregex_iterator a(text_to_search.begin(), text_to_search.end(), r), 
> b;
> std::string::const_iterator last_end = text_to_search.begin();
> 
> while(a != b)
> {
>     result_text.append(a->prefix());
>     result_text.append(my_transformation(a.str()));
>     last_end = (*a)[0].second;
>     ++a;
> }
> result_text.append(last_end, text_to_search.end());
> 
> The key part here is my_transformation(x) which should accept a string and 
> return the new string: use lexical_cast to convert between strings and 
> numbers as required.
> 
> HTH, John. 
> 
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