?
Solved

static member variables

Posted on 2002-03-31
5
Medium Priority
?
207 Views
Last Modified: 2010-04-02
The following code fragment compiles fine with MSVC++ 6.

-- AlienShip.h

class AlienShip : public Sprite  
{
...
private:
     static HBITMAP m_hSprite;
...
};

-- AlienShip.cpp

#include "AlienShip.h"

HBITMAP AlienShip::m_hSprite = NULL;
...

Later, I load a bitmap with the help of the bitmap handler, and use this static variable -m_hSprite- throughout my program. (In fact, this is irrelevant, it's just supposed to give you an idea.)

Now, I'm thinking of doing an animation, and I need 7 bitmap handlers. I couldn't find anything said on static member variable arrays, so tried the following:

-- AlienShip.h

class AlienShip : public Sprite  
{
...
private:
     static HBITMAP m_hSprite[7];
...
};

-- AlienShip.cpp

#include "AlienShip.h"

HBITMAP AlienShip::m_hSprite[0] = NULL;
...


and received the following error message: error C2466: cannot allocate an array of constant size 0.
I tried some other combinations hoping that they would work, but no.

So, the point is, can I do what I want? If yes, how? Please note that I need to use static.
0
Comment
Question by:kushcu
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 30

Accepted Solution

by:
Axter earned 480 total points
ID: 6909453
Try the following:

HBITMAP AlienShip::m_hSprite[7] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL};
0
 
LVL 86

Expert Comment

by:jkr
ID: 6909495
In other words (and I think that is what Axter wanted to say): You'd better be sure to actually initialize a static mamber...
0
 

Author Comment

by:kushcu
ID: 6909904
Axter, thanks! Could you also please tell me why it doesn't work the other way around? (some simple comment would help.)
0
 
LVL 30

Expert Comment

by:Axter
ID: 6910114
The class declaration is declaring an array of 7, but the variable initiation is declaring an array of zero.

Just the fact that it's zero will make the compile fail to compile the code.

Example:
int main(int argc, char* argv[])
{
 char xyz[0] = NULL;//This line fails to compile
 char xyz2[0];//This line also fails to compile
 return 0;
}

Now if you wanted to just initiate the first item in the array, you could still do that, as long as the array is more then zero, and it matches the class declaration.
Example:
HBITMAP AlienShip::m_hSprite[7] = {NULL}; //Use brackets for an array.

0
 

Author Comment

by:kushcu
ID: 6910362
OK, that clears up the issue for me. Thanks for the help.
0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction This article is the first in a series of articles about the C/C++ Visual Studio Express debugger.  It provides a quick start guide in using the debugger. Part 2 focuses on additional topics in breakpoints.  Lastly, Part 3 focuses on th…
Many modern programming languages support the concept of a property -- a class member that combines characteristics of both a data member and a method.  These are sometimes called "smart fields" because you can add logic that is applied automaticall…
The goal of the video will be to teach the user the concept of local variables and scope. An example of a locally defined variable will be given as well as an explanation of what scope is in C++. The local variable and concept of scope will be relat…
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.
Suggested Courses
Course of the Month14 days, 7 hours left to enroll

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question