Array Decaration In C#

Question

1.82/5 (3 votes)

See more:

Hello All,

I've seen a declaration in a class like below:

C#

public class MyClass : IDisposable
{
   double[,] MyDouble;

   public MyClass()
   {

   }

   public void Dispose()
   {
   }
}

Two quick questions. In the absence of private or public, it's private right? And what does the [,] mean? Is that an open ended array?

Posted 21-Mar-13 7:13am

BBatts

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Erik Rude · Accepted Answer · 2013-03-21T07:19:00

Solution 1

[,] is a Multidimensional array as described here : [^]
and yes private as found here [^]

Posted 21-Mar-13 7:19am

Erik Rude

Updated 21-Mar-13 7:38am

v2

Sergey Alexandrovich Kryukov · Accepted Answer · 2013-03-21T07:28:00

No. Arrays are never open-ended; their dimensions are even immutable (please see below).

It simply means that the dimensions of the array are not known at the point of the array variable declaration, but then the array object is never created. When you create an array object itself using new, you always pass dimensions to it, and since that the array dimensions cannot be modified.

Why using an unknown dimensions then? Oh, this is very important.

This is the abstract interface to a variable. [EDIT] First of all, the variable declaration declared the array rank (number of indices to be use, 2 in case of [,], 3 for [,,], etc.); I'm adding this explanation thanks to the good comment by Matt T Heffron (see comments below); thank you, Matt. [END EDIT]. The dimensions can be variables. For example, you create an array in a method, so, in one call, you create the actual object with one set of dimensions, in other call, with different dimensions. When you use the variable referencing already created array object, you inquire about actual dimensions from the array object itself:
http://msdn.microsoft.com/en-us/library/system.array.length.aspx[^],
and, in case of rank > 1: http://msdn.microsoft.com/en-us/library/system.array.getlowerbound.aspx[^],
http://msdn.microsoft.com/en-us/library/system.array.getupperbound.aspx[^].

And, be careful with System.Array.Resize: the array is never actually resized: in fact, a brand-new array object is created, available data is copied from "old" array object to "new" one and returned. If you overwrite the variable with this brand-new array, "old" array object will eventually be garbage-collected.

[EDIT]

For open-ended data structures, you can use collections:
http://msdn.microsoft.com/en-us/library/system.collections.aspx[^],
mostly http://msdn.microsoft.com/en-us/library/system.collections.generic.aspx[^].

Basically, that's all you need to know.

—SA