Question

Possible Duplicate:
Error on calling default constructor with empty set of brackets

Why does the following code compile without problems but when I switch the line

MCl<char, a> tryout;

to

MCl<char, a> tryout();

I receive “error C2228: left of ‘.ea’ must have class/struct/union” ? Isn’t tryout() a call to the default constructor?

Here’s the full code

template <class T, T myval> class MCl
{
public:
    T ea;
    MCl() : ea(myval)
    {
    }
};

int main()
{


    const char a = 'e';
    MCl<char, a> tryout;
    // MCl<char, a> tryout();

    cout << tryout.ea;

    return 0;
}

Answer 1

MCl<char, a> tryout();

declares function tryout, that receives nothing and returns MCl<char, a>.

n3337 8.2/1

the choice is between a function declaration
with a redundant set of parentheses around a parameter name and an object declaration with a function-style
cast as the initializer. Just as for the ambiguities mentioned in 6.8, the resolution is to consider any construct
that could possibly be a declaration a declaration. [ Note: A declaration can be explicitly disambiguated by
a nonfunction-style cast, by an = to indicate initialization or by removing the redundant parentheses around
the parameter name. —end note ]