C / C++ / MFC

29-Sep-04 15:29

Hi,
May be very simple question, but I can't find the answer. Please help me.

class A{
public:
const int My_some_const;
int k;
A(int k_):k(k){};
}

class B:public A{
B(int k):A(k) //<---How to initialize Mysome_const without passing the value througth constructor of A????
}

Thanks in advance,
Boni
Confused | :confused:

Ryan Binns29-Sep-04 18:11

29-Sep-04 18:11

Boniolopez wrote:
How to initialize Mysome_const without passing the value througth constructor of A????

Why? What's wrong with using the constructor?

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

Boniolopez29-Sep-04 22:22

29-Sep-04 22:22

The constructor of B must have the described signature Confused | :confused:

(specific for the application)

Ryan Binns30-Sep-04 0:54

30-Sep-04 0:54

Boniolopez wrote:
The constructor of B must have the described signature

Sorry, I still don't understand what the problem is. Are you saying you're not allowed to explicity call A's constructor?

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

Alan Chambers30-Sep-04 1:14

Alan Chambers

30-Sep-04 1:14

class A {
public:

const int My_some_const;
int k;

A(int k_) : k (k) {};
}

class B : public A {
B(int k) : k(k), My_some_const(1) { };
}

Is that what your looking for? That initialises both member variables without going through the base constructor

"When I left you I was but the learner, now I am the master" - Darth Vader

Boniolopez30-Sep-04 5:26

30-Sep-04 5:26

Hi Alan,
I want to do exactly das wat you wrote. Unfortunetly your solution (was my solution too Smile | :)

is not compilable. It produces error C2758. The same stuff with tamplate produces error C2614.
Any help is very appreciated!!!

22491730-Sep-04 18:21

224917

30-Sep-04 18:21

When looking form base class, it dosen't know someone is going to derive from it and its const will be initilized there.

There is no spoon.

mail

Andrzej Markowski30-Sep-04 21:40

Andrzej Markowski

30-Sep-04 21:40

You can't use the assigment operator to intialize My_some_const because My_some_const is a const member of the class and cannot appear on the left side of an assignment statement. The only way to initialize My_some_const is via constructor member initialization list.

That initializes My_some_const to 10:

class A{
public:
const int My_some_const;
int k;
A(int k_):k(k),My_some_const(10){};
}

class B:public A{
B(int k):A(k)
}

Boniolopez1-Oct-04 4:05

make multiple mdi child windows scroll together

1-Oct-04 4:05

Thanks all for your help

mickelliot29-Sep-04 15:20

mickelliot

29-Sep-04 15:20

Hi there,

I have an mdi app, child window containing a cscrollview. Obviously the user can create new child windows using the window>New Window menu item. When they have created more than one view, I would like the multiple child windows to scroll synchronously. I mean that when an active child window's view is scrolled, all the other child window's views scroll along at the same time.

I can't think of a way to do this! I tried maintaining a CPoint in the document class, updated by the view whenever it is scrolled, and adding a ScrollToPosition command in the update function of the view. But it was very messy and didn't quite work correctly.

Does anybody know if there's a neat clean way I can do this, perhaps sending windows messages directly between child windows or something?

Thanks for any help,

Mick

Re: make multiple mdi child windows scroll together

Ryan Binns29-Sep-04 18:14

Re: make multiple mdi child windows scroll together

29-Sep-04 18:14

mickelliot wrote:
When they have created more than one view, I would like the multiple child windows to scroll synchronously.

Any reason why? The whole point of the New Window menu item is so that users can see different parts of the same document at once. Having them all automatically scroll to the same point sort of defeats the purpose.

Ryan

"Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"

mickelliot30-Sep-04 6:13

mickelliot

30-Sep-04 6:13

Hi Ryan,

Thanks for replying.

The idea is that each view will contain the same view of the same data, but with different parameters so that the view "looks" different. I can best explain myself by asking you to imagine an MDI bitmap editor. You load in a bitmap, which appears in a new child frame, and set its magnification to 100%. You then open a new window and set the magnification of the new view to 200%. Now, when you scroll around the 100% view, you want the 200% view to move along with it appropriately (i.e. in the same direction and twice as fast), so that each view contains the same area of the bitmap but just at different magnifications.

The idea would be to make this an option for the user - i.e. they can either open two child windows and use them to view different parts of the document, or they can adjust the parameters of each view and synchronize the two windows.

Mick

Re: make multiple mdi child windows scroll together

Ryan Binns30-Sep-04 13:48