Re: [Boost-users] RegExp - Callback function

From: Kirit Sælensminde (kirit.saelensminde_at_[hidden])
Date: 2007-10-27 03:15:37

Golan Trevize wrote:
> // the callback function 
> string add5(string x) 
> { 
> int v; 
> v =atoi(x.c_str()) + 5; 
> string vystup = (char *)v; 
> return vystup; 
> } 

I'm not sure about the regex problem, but I think that the callback 
doesn't do what you think it does.

The first part does convert the number in x into its value + 5 in v, but 
the the second part doesn't convert v into a string.

I think Boost.Lexical cast will help here, or you can use a 
std::stringstream:

std::stringstream ss;
ss << v;
string vystup = ss.str();

You used a C style cast, (char *)v, which is generally a pretty bad idea 
in C++. The C++ casts (static_cast, dynamic_cast etc.) have better type 
safety than the C ones. By using a C cast you've turned off the type 
checking, but the type checker was trying to tell you something about 
the expression - shutting it up doesn't make the problem go away.

K