Stack structure after function call with parameters

Question

I was just looking into the memory allocation of a program in C. I know that all the global and static variables are stored in a heap. Also, the stack stores all the function calls. I do have one doubt here though. Say I am calling the following function:

int ret;
int num = 10;
int arr[3] = {1,2,3};
int *ptr = &arr[0];
ret = giveNumber(num, ptr);

Here, I read that the parameters of the function call giveNumer() would also be stored in the same stack. But in what order will they be stored? If I popped the top of stack, which parameter will be popped first, num or ptr?

Depends on your architecture and has nothing to do with your debugger. — Mat
– Mat, Commented Apr 9, 2012 at 17:12

Alok Save · Accepted Answer · 2012-04-09 17:13:01Z

3

I know that all the global and static variables are stored in a heap.
No, thats not true.
As per the standard they are stored in implementation defined memory regions, typically the Data segment and the BSS.

If I popped the top of stack, which parameter will be popped first, num or ptr
The order of evaluation of arguments to a function is Unspecified.
So it depends on your compiler implementation. An compiler might evaluate the arguments from:

Left to Right or
Right to Left or
Any other random order

So the behavior & order you see would depend on this.

answered Apr 9, 2012 at 17:13

Alok Save

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Pavan Manjunath · Accepted Answer · 2012-04-09 17:18:36Z

0

Adding to what @Als has already mentioned, most of the compilers on x86 follow _cdecl calling convention where arguments are evaluated from right to left. Learn more here

http://en.wikibooks.org/wiki/X86_Disassembly/Calling_Conventions#Standard_C_Calling_Conventions

answered Apr 9, 2012 at 17:18

Pavan Manjunath

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