Defining a large array of size larger than a unsigned int limit.

Question

Hello,

I need to define an array statically (in a *.h) file of size 12884901888 like.

unsigned char sram[12884901888]; //All of my code is C.

Above declaration gives error and does not work.

Because constants used in array declarations are unsigned int. But the constant i need to use (12884901888) is larger than the unsigned int limit.

How can i define the array as above, of size 12884901888 ?

Thank you.

-AD

P.S. I know many will say, optimize on that humongous array size, but i need to use same for some reason specific to my case.

Answer 1

Make the array dimension an unsigned long long.

unsigned char sram[12884901888ULL];

Answer 2

Is this for an embedded microcontroller? You can often get away with something like:

#define sram (*((unsigned char (*)[1]) 0))

Unless your compiler implements bounds checking, the array size does not matter. In any case you do not want the compiler to attempt to reserve 12884901888 bytes, because linking will fail.