Why is there no call to the constructor? [duplicat

Question

This question already has an answer here:

• Default constructor with empty brackets 9 answers

This code doesn't behave how I expect it to.

#include<iostream>
using namespace std;

class Class
{
    Class()
    {
        cout<<"default constructor called";
    }

    ~Class()
    {
        cout<<"destrutor called";
    }
};

int main()
{    
    Class object();
}

I expected the output 'default constructor called', but I did not see anything as the output. What is the problem?

Answer 1

No call to constructor

Because the constructor never gets called actually.

Class object(); is interpreted as the declaration of a function object taking no argument and returning an object of Class [by value]

Try Class object;

EDIT:

As Mike noticed this is not exactly the same code as what you are feeding to the compiler. Is the constructor/destructor public or is Class a struct?

However google for C++ most vexing parse.

Answer 2

Nope. Your line Class object(); Declared a function. What you want to write is Class object;

Try it out.

You may also be interested in the most vexing parse (as others have noted). A great example is in Effective STL Item 6 on page 33. (In 12th printing, September 2009.) Specifically the example at the top of page 35 is what you did, and it explains why the parser handles it as a function declaration.

Answer 3

You can use it like this:

Class obj;
//or
Class *obj = new Class(/*constructor arguments*/);