Difference between constructor calls with and without ( )

Question

I\'m a C++ beginner and would like to understand why

return std::list();

needs parentheses, but

std::list         


        

Answer 1

look at it this way:
1) you need to create an object
2) you need to return it.

let's say the compiler looks at the expression return Foo; , the compiler thinks "hey! he wants me to return a type! a type is not a thing that I can return! I need a true variable here!"

so you can write something like

Foo temp;
return temp;

or make it shorter - call the default constructor of Foo , then return the Anonymous object I just created. you treat the constructor as a function that produces an object.

does the code return createDefaultFoo(); looks much more reasonable? well, this is what Foo() does, it creates and returns anonymous Foo obejct

in this line :

std::list foo;

the compiler can tell you want an object named foo from the type std::list. so the () are redundand. as answered here, adding the () will make the compiler think you declare a function.