Question

Possible Duplicate:
Do the parentheses after the type name make a difference with new?

Whats the difference between the following initialisations? In the tutorial, it is as in case #1 but does it make any difference if i use the #2 way below?

struct X
{
    X() {}
    int x;
};

int main()
{
    std::auto_ptr<X> p1(new X);   // #1
    std::auto_ptr<X> p2(new X()); // #2
}

Answer 1

The smart pointer doesn’t make any difference here. Both smart pointers are initialized in the same way, with a pointer to X. The difference is how X is initialized. If there is a difference and what the difference is depends on how X is defined. This answer has an excellent description of what happens in different cases. In this case since X has a default constructor they get initialized the same. However if there were no default constructor they would be initialized differently.