Does values of array destroyed when we reallocates a array in c#?

Question

I was working with my project in Visual studio in c#, but one thing I don't know about is that when we reallocate a array (no matter what type it is of) then does the previous values that stored in the array are destroyed or they are not? For Example:

int[] a=new int[2];
a[0]=200;
a[1]=400;

Now I reallocated the array 'a' with 4 elements:

a=new int[4];

Now, does the previous values will be there or they changed to something new value, i mean garbage, zero or they will be as they was? I also tried it myself in visual studio, and value didn't changed, but I want to be sure if really they don't.

Answer 1

Doing this:

a = new int[4];

you set a to point to another array in another memory region.

If there is no another references to old array it will be in memory until next garbage collection clears it.

Answer 2

When you have any other references to the former array it still stays in memory.

int[] a=new int[2];
a[0]=200;
a[1]=400;

int[] additionalReference = a; // The array stays in memory 
a = new int[4];

Otherwise the garbage collector handles the array (see Fundamentals of Garbage Collection).

Check the documentation of Array.resize:

This method allocates a new array with the specified size, copies elements from the old array to the new one, and then replaces the old array with the new one.array must be a one-dimensional array.