Does the size of pointers vary in C? [duplicate]

Question

Possible Duplicates:
Can the Size of Pointers Vary Depending on what’s Pointed To?
Are there are any platforms where pointers to different types have different sizes?

Is it possible that the size of a pointer to a float in c differs from a pointer to int? Having tried it out, I get the same result for all kinds of pointers.

#include <stdio.h> #include <stdlib.h>  int main() {     printf("sizeof(int*): %i\n", sizeof(int*));     printf("sizeof(float*): %i\n", sizeof(float*));     printf("sizeof(void*): %i\n", sizeof(void*));     return 0; } 

Which outputs here (OSX 10.6 64bit)

sizeof(int*): 8 sizeof(float*): 8 sizeof(void*): 8 

Can I assume that pointers of different types have the same size (on one arch of course)?

Answer 1

Pointers are not always the same size on the same arch.

You can read more on the concept of "near", "far" and "huge" pointers, just as an example of a case where pointer sizes differ...

http://en.wikipedia.org/wiki/Intel_Memory_Model#Pointer_sizes

Answer 2

In days of old, using e.g. Borland C compilers on the DOS platform, there were a total of (I think) 5 memory models which could even be mixed to some extent. Essentially, you had a choice of small or large pointers to data, and small or large pointers to code, and a "tiny" model where code and data had a common address space of (If I remember correctly) 64K.

It was possible to specify "huge" pointers within a program that was otherwise built in the "tiny" model. So in the worst case it was possible to have different sized pointers to the same data type in the same program!

I think the standard doesn't even forbid this, so theoretically an obscure C compiler could do this even today. But there are doubtless experts who will be able to confirm or correct this.