Displaying the amount of memory allocated

Hi I'm writing some test stuff to see the amount of memory that allocated displayed correctly

in Windows TasK manager. Below is the code;

int main(int argc,char* argv[])
{
 struct stat st;
 char commandXCopy[2开发者_运维知识库00];
 char commandDelete[200];

 char *fNames[2^16];
 int i =0;
    char *ptr = (char *)malloc(sizeof(char) * 2^32);
     printf("\nTEST");

    if(!ptr)
            printf("\nCan not allocate");
    else
            printf("\nMemory allocate");


     while(1==1)
     {
     };

I try to make huge allocations from stack and heap. But all I see on task manager->processes is ~800K.

And I don't see "Can not allocate" message either.

I have Windows 32bit XP Pro and use gcc and application is a dos application.

gcc test.c

Regards

I think you may be suffering under a misapprehension: 2^32 is not 2³² (4G, assuming your bytes are eight bits long, which I will for the purposes of this answer) in C.

^ is the bitwise XOR operator. So what you're actually allocating is:

     binary        hex     decimal
    ---------      ----    -------
    0010 0000      0x20      32
xor 0000 0010      0x02       2
    =========
    0010 0010      0x22      34

or 34 bytes. Similarly, 2^31 would give you 29 bytes so what you may think should be a 2G difference (2³² - 2³¹) is really only 5 bytes.

If you want to do powers in C, you should look at the pow() function but I doubt you'll be able to get 4G of memory (perhaps on a 64-bit OS but even then, that's an awful lot).

And just one other thing: sizeof(char) is always 1 - there's no need to multiply by it.