Back to General and Gameplay Programming

class declrations and #include

General and Gameplay Programming Programming

Started by mse61 February 22, 2002 11:38 PM

4 comments, last by mse61 22 years, 1 month ago

mse61

122

Author

February 22, 2002 11:38 PM

I define one class in one file and another in a second file like this:


class A
{
    B var1;
};

// in second file
class B
{
    A var2;
};

I''ve tried to declare the class ahead of the implmentation like this:


class A;
class B
{
    A var2;
};

but i still get errors about undefined classes. This problem is really eating up important time, and I''m out of ideas. HELP! ~mse61 "Today UNIX command is: exop - execute operator" ICQ: 122419859 AIM: ThePhantomTIE e-mail: randlem@bgnet.bgsu.edu

++mse61--ICQ: 122419859AIM: mse6102

Null and Void

1,088

February 22, 2002 11:45 PM

Your first example is impossible since it takes infinite amounts of memory to store. A has a B which has an A which has a B, et cetera. You can have a pointer to B in A, and vice versa, using the second method.

mse61

122

Author

February 23, 2002 12:08 AM

Errr...wrong example...here is the correct one.

class A{   B var1;};// in other fileclass B{   float array[4][4];};void Some_Function(A var2);

~mse61

"Today UNIX command is: exop - execute operator"

ICQ: 122419859
AIM: ThePhantomTIE
e-mail: randlem@bgnet.bgsu.edu

++mse61--ICQ: 122419859AIM: mse6102

Gorg

248

February 23, 2002 12:17 AM

Forward declarations can only be used for reference or pointers because if you write( say there is a class called myClass)

class OtherClass
{
myClass A;
}

then the compiler needs to know the correct size of myClass to be able to correctly compiler OtherClass, but

class OtherClass
{
myClass* A;
}

or

class OtherClass
{
myClass& B;
}

Then, it does not need to know the full size of myClass, because they are declared as pointers and pointers have a known size.

I do not think I have been clear enough, but that''s life!

Anonymous

February 23, 2002 02:15 AM

just swap round the order of the A and B declarations and you''ll be sweet

dword2002

122

February 23, 2002 03:53 AM

Anyway, the pointer/reference is the best solution. If you only have two classes the problem is still easy to solve (swap). But what about 10-20 classes?

DworD

DworD

class declrations and #include

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

class declrations and #include

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Reticulating splines