Please explain this output

[rajimrt]

#include <string>
#include <iostream>
using namespace std;

class AAString
{
public:
    AAString()
    {   
        cout << "AAString()" << endl;
    }   
    
    AAString(int i = 2)
    {   
        cout << "AAString(int)" << endl;
    }   

    ~AAString()
    {   
        cout << "Destroyed.." << endl;
    }   
};


int main()
{
    cout << "Started" << endl;
    AAString obj();
    cout << "object created." << endl;
    cout << "Address of the object:" << &adlkjlkf << endl;
    return 0;
}

Started
object created.
Address of the object:1

Please explain why this object is created on memory location 0x1.

Thanks

[Disch]

It's not.

There are a few things wrong with your code.

    AAString obj();

This doesn't create an object. It defines a function. Lose the parenthesis.


Also:

cout << "Address of the object:" << &adlkjlkf << endl;

I don't know what you expect adlkjlkf to be, but you never declared any object by that name.


This code wouldn't even compile.

[rajimrt]

I'm sorry that line should be

cout << "Address of the object:" << &obj<< endl;

[mindfog]

AAString obj();??? If you are trying to create an object you should change it to AAString obj;

[rajimrt]

Why? I have used default value for overloaded constructor.

Therefore AAString(int i = 2) shouldn't be called when I create the object?

Also I need to know why it prints 1 for address of obj.

[mindfog]

No. You should call it like AAString obj = AAString(); which is not correct for your code because it is not clear. May be you can try AAString obj = AAString(3) or deleting the default constructor.

Your code doesn't print address of an object because there is no object.

Edit: I missed a thing, if you delete AAString(); then AAString obj() should work if you give a value. If you want to use default value then you do AAString obj;

[DSLq5Di1]

http://www.parashift.com/c++-faq-lite/ctors.html#faq-10.4

[rajimrt]

I changed the code to this

#include <string>
#include <iostream>
using namespace std;

class AAString
{
public:
    //AAString()
    //{ 
    //  cout << "AAString()" << endl;
    //} 
    AAString(int i = 8 ) 
    {   
        cout << "AAString(int)" << endl;
    }   
    ~AAString()
    {   
        cout << "Destroyed.." << endl;
    }   
};


int main()
{
    cout << "Started" << endl;
    AAString objct();
    cout << "object created." << endl;
    cout << "Address of the object:" << &objct << endl;
    return 0;
}

but no difference in the output

Started
object created.
Address of the object:1

[mindfog]

Hmm i think because of the compiler you use, it doesn't recognize it. Try AAString objct = AAString();

[z05DSL3A]

rajimrt,
AAString objct(); What do you think this line is doing? [Hint: it is not creating an object]

[mindfog]

@Grey Wolf +1.

You keep trying the same thing. Look AAString objct(5); would work but AAString objct(); wouldn't work. If you want to use the default value you should write AAString objct = AAString();.

[z05DSL3A]

to create an object of type int, with its default constructor, you would write:
int x;
if you wanted to create it with a value:

int x= 8;  // or
int y(8);

so for your class, creating an object with the default constructor is:
AAString objct;
if you wanted to create it with a value:
AAString objct(4);

[rajimrt]

If AAString objct() does not create an object of AAString what else does it do?

Please give me a reference to read about this.

[firedraco]

sloppy9 wrote:

http://www.parashift.com/c++-faq-lite/ctors.html#faq-10.4

[rajimrt]

Thank you firedraco, but your reference does not tell me why any of two constructors are not called when I use AAString objct()

[z05DSL3A]

It declares a function called objct that returns an AAString.

http://www.parashift.com/c++-faq-lite/ctors.html#faq-10.2

[Nisheeth]

why any of two constructors are not called when I use AAString objct()

Because it is creating a call to a function called objct() that returns data of type AAstring

EDIT:
Corrected a mistake.

[Disch]

*ahem*

I in my first reply wrote:

This doesn't create an object. It defines a function. Lose the parenthesis.

=P