in c# ,one array of class and two connected instance of it why ?

Question

Hi I wrote the code below :

1. MyClass[] origArr=new MyClass[3];  
2. MyClass[] arr1;
3. // filled the array with objects and did some work on it .  
4. dgv_1.DataSource=origArr;  
5. 
6. // Here is the problem :
7. arr1=origArr;  
8. // do some work on arr1 ...  
9. dgv_2.DataSource=arr1;  

For some reason the data in 'origArr' changed when data in 'arr1' change ...
I thought that maybe this happened because 'origArr' and 'arr1' are pointers referring to the same object so I changed line '7' to :

7. origArr.CopyTo(arr1,0);

but it didn't work ... what can i do to make the pointers referring to different objects?

Answer 1

Your line 7 copies the reference to origArr into arr1, so they point to the same physical array.

Even a Clone or CopyTo won't help much: you will get a copy of the array structure, but in there the references to your oringinal classes are copied. So you end up with a new array with still the same objects.

You will need to Clone your MyClass objects and put those clones into a new array.

Answer 2

In c# variable holds reference, not the value. to copy it do

MyClass[] origArr=new MyClass[3];  
MyClass[] arr1 = new MyClass[3];
origArr.CopyTo(arr1,0);

you have to allocate memory by yourself

Answer 3

You need to change line 7 to origArr.CopyTo(arr1,0); as you noted. But you also need to initialize the arr1 array.

1. MyClass[] origArr=new MyClass[3];   
2. MyClass[] arr1=new MyClass[3];  

Answer 4

try to use

Array.Copy(src , dest, lenght)