Re: [Boost-users] RegExp - Callback function

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.

------------ Původní zpráva ------------ Od: John Maddock Předmět: 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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