Re: Default parameters - problems

[anitha boyapati]

Hi John,

> > using namespace std;
> > class test {
> >       public :
> >               test() { };
>
> I was surprised that g++ compiled your code (after removing the first
> function and leaving the overloaded one) although you have a semicolon
> after the function test(), which is something I've never seen before and
> thought was invalid !!!

 Its a pretty much common pratice in the enviroment I work - although
an inelegant one.
 But why should it not work ?


> >
> > test.cc: In function `int main()':
> > test.cc:11: error: call of overloaded `func1(const char[6], const
> > char[6], bool)' is ambiguous
> > test.cc:3: note: candidates are: void test::func1(std::string, bool, int)
> > test.cc:6: note:  void test::func1(std::string, std::string, bool)
> >  Why is this not compiling ? Can somebody explain what is going on here ?
> >  Why is it not directly going to overloaded func1 () - declared second. ?


> This leaves the second argument, which actually surprised me, that the
> compiler get confused whether to convert "world" into a string or a
> bool. After a while I realized that "world" is neither a string nor a
> bool, instead it is a char array,  which requires the compiler to cast
> it to either type, thus the candidates mentioned above. In other words,
> if string(const char*) can convert the char* to a string, then certainly
> static_cast<bool>() can convert the char* to a bool also. This makes the
> compiler confused about which of the two functions is to be called.

I didnot think about static_cast<bool> or casting either for that matter.

> A workaround to that is to call the overloaded function as follows:
> t->func1("hello", string("world"), false);//This will work

 Yes. It worked. Thanks for the information and workaround.


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Anitha Boyapati