Create too large array in C++, how to solve?

Question

Recently, I work in C++ and I have to create a array[60.000][60.000]. However, i cannot create this array because it\'s too large. I tried float **array

Answer 1

To initialise the 2D array of floats that you want, you will need:

60000 * 60000 * 4 bytes = 14400000000 bytes

Which is approximately 14GB of memory. That's a LOT of memory. To even hold that theoretically, you will need to be running a 64bit machine, not to mention one with quite a bit of RAM installed.

Furthermore, allocating this much memory is almost never necessary in most situations, are you sure no optimisations could be made here?

EDIT:

In light of new information from your comments on other answers: You only have 4GB memory (RAM). Your operating system is hence going to have to page at least 9GB on the Hard Drive, in reality probably more. But you also only have 20GB of Hard Drive space. This is barely enough to page all that data, especially if the disk is fragmented. Finally, (I could be wrong because you haven't stated explicitly) it is quite possible that you're running a 32bit machine. This isn't really capable of handling more than 4GB of memory at a time.