shadowed parameter

Question

why is the second constructor shadowing the first?

class RC2{
    private;
        bool keyset;
    public:
        RC2(uint32_t t1 = 64){
            keyset = false;
        }

        RC2(const std::string KEY, uint32_t t1 = 64){
            RC2(t1);
            //setkey(KEY);
        }
};

is giving me: error: declaration of 'RC2 t1' shadows a parameter

i would think that there is no way for the compiler to mess up distinguishing between these

im using codeblocks gcc with C++0x

Answer 1

Because RC2(t1); is a local variable declaration shadowing argument t1, not a call to the other constructor. The following code is also valid:

int main(int argc,char* args[])
{
  int(a);
  a = 2;
  return a;
}

Note! Before C++11, there was no way to call another constructor on the same class from an constructor in C++. If you are using an old C++ version make an Init()-method which both constructors invoke.

Answer 2

The error is not triggered by the constructor declaration.

The error is raised on the line that declares a variable t1 of type RC2 in the block of the second constructor. This variable shadows the similarly named t1 variable passed a an argument to the constructor.

I guess your intention with RC2(t1); was to call the other constructor, but this is not possible in C++. It will be possible in C++2011, but using another syntax.