C++ Classname Function()

Question

I was recently giving an online quiz on c++ and a question came that had similar syntax as

class className
{
     public:
     constructor()
     {
         print("ABC");
     }
}

int main()
{
    className ABC();
    return 0;
}

I thought it would not compile but rather it compiled and ran without having any effect, I am interested as to what feature this is and in which case do we use this?

`className ABC();` declares a function pointer. Use `className ABC;` to create a local object. And a method named `constructor` isn't a constructor. — Alex Shesterov, Oct 03 '18 at 12:37
Also the constructor is a function with the same name as the class, like `className() { ...` not a method named constructor. — Fantastic Mr Fox, Oct 03 '18 at 12:39
Such example [didn't compile](https://wandbox.org/permlink/lTF1vJYruVQebH7i) for me. — Algirdas Preidžius, Oct 03 '18 at 12:41
@Swordfish https://stackoverflow.com/questions/1424510/my-attempt-at-value-initialization-is-interpreted-as-a-function-declaration-and — Algirdas Preidžius, Oct 03 '18 at 12:42
@AlgirdasPreidžius `className ABC();` DOES NOT declare a function pointer.` No links you throw at me change that fact. — Swordfish, Oct 03 '18 at 12:43
Does not compile on Ubuntu, g++v7.3: error: ISO C++ forbids declaration of ‘constructor’ with no type [-fpermissive] for line "constructor()..."; Also, the code requires a ';' after class definition. — 2785528, Oct 03 '18 at 12:45

score 1 · Answer 1 · answered Oct 03 '18 at 12:39

Your posted code won't compile. Ignoring that there are 2 reasons it doesn't do anything.

className ABC(); declares a function. To call the default constructor of a class simply omit the brackets: className ABC;
className has a method called constructor but no contructor so doesn't print anything when it is constructed.

C++ Classname Function()

1 Answers1