这是我可以为一个进程保留的最大内存吗？

Question

char bytes[0x7FFFFFFF]; /* this? */

int main()
{
    return 0;
}

Over 2Gb? (if i calc it right)

I'm in a 32bit system, with 4Gb of memory. In a different system that would be more or less?

Answer 1

First off, this is going to be dependent on a number of factors like platform and even configuration on the platform. The max address space available to a 32-bit process is typically restricted by where the user/kernel space split is, which often is either 3G/1G or 2G/2G (user/kernel).

Now, likely creating an array like that won't actually "reserve" all that memory. Rather it would be mapped into the virtual address space and wouldn't actually start consuming memory until it's accessed (see: on demand paging).

Also, remember that you have to share your address space with everything else in your program, including the code. If you consumed all of that with an array, where would your code go?

Answer 2

It depends by:

• the compiler
• the system
• the OS

If you're running on win32, you are not even using your 4GB or RAM!