Read only two-dimensional array in C#

Question

Is there any established way of returning a read-only 2-d array in C#?

I know ReadOnlyCollection is the right thing to use for a 1-d array, and am happy to write my own wrapper class that implements a this[] {get}. But I don't want to reinvent the wheel if this wheel already exists.

Here are some answers from a similar question on StackOverflow - http://stackoverflow.com/questions/678379/is-there-a-read-only-generic-dictionary-available-in-net — Scorpion-Prince, Apr 18 '12 at 21:14
Perhaps a ReadOnlyCollection, each of whose elements is also a ReadOnlyCollection? — Mark Reed, Apr 18 '12 at 21:16
@Scorpion-Prince: and Op's says that he is aware that can implement kind of wrapper. — Tigran, Apr 18 '12 at 21:16
@MarkReed That would be easy for a jagged array. For a non-jagged array copying the data wouldn't be as trivial. — Servy, Apr 18 '12 at 21:17
@MarkReed that would be more trouble to implement than it's worth ... unless sblom is asking about a 2-d jagged array. I had assumed he meant a proper 2-d array, like `T[,]` rather than `T[][]`. — phoog, Apr 18 '12 at 21:19
Yes, more like `T[,]` than `T[][]`, although it isn't a _huge_ deal for me. — sblom, Apr 18 '12 at 21:34

score 3 · Answer 1 · answered Apr 18 '12 at 21:16

Unfortunately there is no any built-in implementation to handle a case you ask for. But a simple implementation on your own, shouldn't be something difficult.

The only think, I hope you aware of it, that you will do is a readonly collection, but not elements inside that collection.

Hope this helps.

JotaBe · Accepted Answer · 2018-10-22T11:08:27.207

There's only one way to simulate this.

You need to create your own class, with a private array.

The most similar implementation of an array is an indexer:

The '10.8' link shows the simulation of a bidimensional array.

If you implement the indexer only with a getter, the user can only read the elements, but not write them. However, if each element is an object (reference type) you can't prevent the modification of the accessed objects properties.

However, there are several ways of simulating "read-only" objects:

Create a wrapper class that exposes the properties of each element in the array as read only properties, so that they cannot be modified
Using primitive value types (like int)
Defeating the changes by returning a copy of the element in the private array instead of the original element in the private array, so that, the changes made to the object don't affect the original object in the array.

In other languages like C++ there are references and pointers to constant values, but this doesn't exist in C#.

The 10.8 link is broken. Here it is on the wayback machine:https://web.archive.org/web/20120103002717/http://msdn.microsoft.com/en-us/library/aa664459(v=vs.71).aspx — David, Oct 22 '18 at 05:13

Read only two-dimensional array in C#

2 Answers2

Linked