C# changing previously assigned values

Question

I have a function that gets called on a two dimensional array "a" and alters the array. However, it also alters any array that was previously assigned to "a", before even calling the function. I'm not sure if I understand why!

char[][] copy;

copy = a; // a is a also a two dimensional char array

DFSfunction(a); //DFSfunction alters values of a

So after DFSfunction is called, values of "copy" is also altered. How can I keep a copy of the original "a"?

Thank you!

do a [deep copy](https://en.wikipedia.org/wiki/Object_copying#Deep_copy) which is achieved wit h`Array.Clone` https://www.geeksforgeeks.org/shallow-copy-and-deep-copy-in-c-sharp/ — phuclv, Apr 28 '21 at 05:03
Technically clone does a shallow copy - but it will be sufficient for chars @phuclv. — mjwills, Apr 28 '21 at 05:09

score 2 · Answer 1 · edited Apr 28 '21 at 05:35

2

Arrays are mutable in C# so if you change a in your example it will have an effect on copy as well, since they still have the same reference

So when you wrote

copy = a

copy is just pointing to the same a array.

To solve this you can use Array.Copy..

In your example it can look something like this :

char[][] copy;
char[][] a;

Array.Copy(a, copy, a.Length);

You can also use Array.Clone :

var copy = (char[][])a.Clone();

edited Apr 28 '21 at 05:35

Mauricio Gracia Gutierrez

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answered Apr 28 '21 at 04:58

Jonas W

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Clone didn't work unfortunately, same thing as before was happening. – Nila Apr 28 '21 at 05:53
and I couldn't get Arary.Copy working, says copy has to be initialized first. – Nila Apr 28 '21 at 05:53
@Nila Pass in the clone to the method - don't pass in `a`. – mjwills Apr 28 '21 at 07:15
A[] Array2 = Array.ConvertAll(Array1,a => (A)a.Clone()); - https://stackoverflow.com/questions/3464635/deep-copy-with-array – Mauricio Gracia Gutierrez Apr 28 '21 at 16:55

C# changing previously assigned values

1 Answers1