Solved

2D Dynamic Arrays

Posted on 2004-10-03
11
199 Views
Last Modified: 2010-04-01
Hi,

How do I make a two-dimensional dynamic array? And is it possible to make one from a class?
0
Comment
Question by:SonicX_BlueBlur
  • 4
  • 3
  • 2
  • +1
11 Comments
 
LVL 55

Expert Comment

by:Jaime Olivares
Comment Utility
Hi SonicX_BlueBlur,

You can design your own class to manage a bidimensional dynamic class.
Have a look to this similar question I've answered for a 3-dimensional dynamic class:
http://www.experts-exchange.com/Programming/Programming_Languages/MFC/Q_21021623.html

Good luck,
Jaime.
0
 
LVL 17

Expert Comment

by:rstaveley
Comment Utility
EE's Axter has this implementation, which he posted a while back, which is nice:

http://axter.com/code/dynamic_2d_array.h
0
 

Author Comment

by:SonicX_BlueBlur
Comment Utility
rstaveley, Axter's code is illegible to me. So far, Jaime's code looks the best, but I don't know how I could make it work with a class.
0
 
LVL 55

Expert Comment

by:Jaime Olivares
Comment Utility
Here is a 2d implementation with a 'double' data member, hope you can understand. I will continue tomorrow because I am going to sleep. Good luck, Jaime.

---------------------------------

class Double2dArray
{
      double *data;   // example with 'double' datatype, could be anything
      int maxx, maxy;

      Double3dArray (int x, int y) {
             maxx = x;
             maxy = y;
             data = new double[maxx*maxy];
      }
      ~Double3dArray () {
           delete [] data;
      }
      inline double GetAt(int x, int y) {
           return data[x*maxy*y];
      }
      inline SetAt(int x, int y, int z) {
           data[x*maxy*y] = val;
      }
};

How to use:

Double2dArray arr(200,200);
arr.SetAt(100,30);    // Set element 100,30
double value = arr.GetAt(100,30);  // Get value of element 100,30

0
 

Author Comment

by:SonicX_BlueBlur
Comment Utility
Yes, I know. I read that same code on that other thread, but how would I call member functions using that 2D array code to make a class array?
0
How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

 
LVL 30

Accepted Solution

by:
Axter earned 145 total points
Comment Utility
http://axter.com/code/dynamic_2d_array.h

If you use my code, you can easily create a 2 Dimensional array using the following method:

dynamic_2d_array<int> MyArrOfInt(33, 44);

Where 33 is one dimension, and 44 is the second.

The above example created and interger array.

Following is a char array:

dynamic_2d_array<char> myarray(row, col);
0
 
LVL 30

Expert Comment

by:Axter
Comment Utility
To access the data in the array, you just use the same syntax as if you were using a C-Style array.

MyArrOfInt[22][11] = 1234;

cout << MyArrOfInt[22][11] << endl;

The dynamic_2d_array class is very generic, simplistic, and efficient.

Since it uses the same interface as a C-Style array, it makes it easier to use and maintain.
0
 
LVL 30

Expert Comment

by:Axter
Comment Utility
>>but I don't know how I could make it work with a class.

To use Jaime's code, you would have to change his original, since it's not a template class.

If you use the dynamic_2d_array, you don't have to change the class.
You just declare it with your class name in the template ID.

dynamic_2d_array<MyClass> my_var(x, y);
0
 

Author Comment

by:SonicX_BlueBlur
Comment Utility
...Geez, it's that easy? And I thought this was all way above my head :P
Thanks for clearing that up, Axter. 145 points to you.
0
 
LVL 17

Expert Comment

by:rstaveley
Comment Utility
I'm glad you accepted that from Axter rather than me. It would have been embarrassing 8-)
0
 
LVL 30

Expert Comment

by:Axter
Comment Utility
>>I'm glad you accepted that from Axter rather than me. It would have been embarrassing 8-)

IMHO, I think the points should have been split.

I steal jkr's answers all the time. :-)
0

Featured Post

Highfive Gives IT Their Time Back

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

Join & Write a Comment

In days of old, returning something by value from a function in C++ was necessarily avoided because it would, invariably, involve one or even two copies of the object being created and potentially costly calls to a copy-constructor and destructor. A…
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 pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.

762 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

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now