I have written following code:
---------------------------
import std.stdio;
class Abc
{
public:
	int	add(int a, int b) { return a + b; }
}
void main()
{
	Abc abc;
	int a = abc.add(1, 2);
}
----------------------------
Upon compilling and building I executed a program. The message appeared: "Error: Access Violation". What should I do to use classes?

On Sat, 21 Apr 2007 12:46:14 +0000 (UTC), Niovol wrote:

> I have written following code:
> ---------------------------
> import std.stdio;
> class Abc
> {
> public:
> 	int	add(int a, int b) { return a + b; }
> }
> void main()
> {
> 	Abc abc;
> 	int a = abc.add(1, 2);
> }
> ----------------------------
> Upon compilling and building I executed a program. The message appeared: "Error: Access Violation". What should I do to use classes?

Firstly, this newsgroup is o longer active. Please use the group "digitalmars.D" next time.

But back to your problem. Unlike C++, D requires that all classes be instantiated before use. That means, you must use a 'new' statement on your object before trying to access it. In D, a simple declaration such as your

  Abc abc;

only allocates space for a null reference.

This should work ...

 import std.stdio;
 class Abc
 {
 public:
 	int	add(int a, int b) { return a + b; }
 }
 void main()
 {
 	Abc abc = new Abc; // Must be instantiated before use.
 	int a = abc.add(1, 2);

        Abc def;
        int b;
        def = new Abc;  // 'new' before use.
 	b = abc.add(3, 4);

 }


-- 

Derek Parnell
Melbourne, Australia
"Justice for David Hicks!"
skype: derek.j.parnell