C++ syntax creating an object that has no parameter

Question

This question might be a little odd and I could not find anything about it on the web. This is mostly about the c++ syntax.

Suppose I have the following struct

struct foo
{
 void someMethod();
};

Now here we could create an instance of this struct and use its method as such

foo().someMethod();       // Works fine - Create instance on stack and called its method
foo* p = new foo(); // Works fine - p points to object on the heap

Now my question is - I have seen in some places the following

foo* p = new foo; //Not new foo(); // Its missing `()` at the end;

so whats the difference between declaring foo in the following two ways for an object that does not require a parameter in the contructor

foo(); and foo;

if there is no difference in the two then why cant we do

foo.someMethod();

this is just a question that I am curious about.

Answer 1

There are some subtle differences, see Do the parentheses after the type name make a difference with new?