OutofMemory Exception Object Array Size

Question

I am trying to capture a spreadsheet data in to a 2D array. I am using VSTO.

int rc = 1048576;
int cc = 1638;

string[,] arr = new string[rc, cc];
         


        

Answer 1

Let's do the math. You are trying to allocate a 2D string array with 1048576 * 1638 = 1717567488 elements. The size of string reference on x64 is 8 bytes => a total of 1717567488 * 8 = 13740539904 bytes. Which is about 13 GB of continuous memory space. Maximum size for single allocation for CLR is 2GB, so you are getting OutOfMemoryException as such single block can't be allocated.

Note that such amount of strings even when all are 1-2 characters long will take 30GB for string values in addition to references. What else than an OutOfMemoryException did you expect to get?