Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
?
Solved

constant trouble.

Posted on 2004-08-04
4
Medium Priority
?
210 Views
Last Modified: 2010-04-01
Hi,
I wish to have an array that will remain constant in my class.

eg.

class A
{
  private:
      const BYTE myData[] = {0x1,0x1,0x1,0x1,0x1};
}


..As you may guess, the compiler throws a syntax error at the '{'.

Whats the best way to achieve this?

TIA

David.
0
Comment
Question by:dave_p_r_b
  • 3
4 Comments
 
LVL 30

Accepted Solution

by:
Axter earned 375 total points
ID: 11715325
You should make this a static variable.
Example:
class A
{
 private:
      static const BYTE myData[5];
};

//In your cpp file
const BYTE A:myData[5] = {0x1,0x1,0x1,0x1,0x1};

0
 
LVL 30

Expert Comment

by:Axter
ID: 11715371
Correction:
//In your cpp file
const BYTE A::myData[5] = {0x1,0x1,0x1,0x1,0x1};

Since you want this to be a constant variable that is set at compile time, there really is no need for each instance of your object to carry an instance of the constant data.
And in fact it would make your code less efficient if you used a non-static data member.

By making it static, you can then initialize it in your *.cpp file.

continue....
0
 
LVL 30

Expert Comment

by:Axter
ID: 11715437
Alternate method:

class A
{
 private:
     const BYTE* GetMyData()
     {
          const BYTE myData[] = {0x1,0x1,0x1,0x1,0x1};
          return myData;
     }
};

You can use above code as in following:
BYTE xx = GetMyData()[2];
0
 
LVL 39

Expert Comment

by:itsmeandnobodyelse
ID: 11728054
Another method (if you don't need sizeof(myData) in your prog)

class A
{
  private:
      const BYTE* myData ;
  public:
      const BYTE* getMyData()
      {  
            BYTE* pData = new BYTE[5];
            for (int i = 0; i < 5; i++)
                  pData[i] = 0x01;
            return pData;
      }
      A() :  myData(getMyData()) {}      
};

However, if all instances have the same data, Axter's static member is the best solution.

Regards, Alex



0

Featured Post

Get expert help—faster!

Need expert help—fast? Use the Help Bell for personalized assistance getting answers to your important questions.

Question has a verified solution.

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

When writing generic code, using template meta-programming techniques, it is sometimes useful to know if a type is convertible to another type. A good example of when this might be is if you are writing diagnostic instrumentation for code to generat…
What is C++ STL?: STL stands for Standard Template Library and is a part of standard C++ libraries. It contains many useful data structures (containers) and algorithms, which can spare you a lot of the time. Today we will look at the STL Vector. …
The viewer will learn how to user default arguments when defining functions. This method of defining functions will be contrasted with the non-default-argument of defining functions.
The viewer will learn additional member functions of the vector class. Specifically, the capacity and swap member functions will be introduced.

579 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