Well, data.str().c_str() yields a char const* but your function Printfunc() wants to have char*s. Based on the name, it doesn’t change the arguments but merely prints them and/or uses them to name a file, in which case you should probably fix your declaration to be
void Printfunc(int a, char const* loc, char const* stream)
The alternative might be to turn the char const* into a char* but fixing the declaration is preferable:
Printfunc(num, addr, const_cast<char*>(data.str().c_str()));
