int *ptr + max possible value

Applications Programming
1

From reading my C book, Im aware that the integers have a maximum value which depends on what type of processor you are using (since they use 16-bit or 32-bit instructions).

Now I know pointers are very flexible, since they can reference anything, but in the case of integer pointers, can they reference an int value beyond the max. value of 4,294,967,295 (Im considering unsigned int * in a 32-bit environment) ?

Reason Im asking is because Im designing a program which reports on my company's disk usage (where some of our files are in the gigabyte and terabyte range)

many thanks

2

Depends in practice on the compiler suite. POSIX and C89 and other standards define constants which you can query and use in your programs; look for MAXINT and friends.

vbvntv$ gcc -E - <<HERE | tail -1
> #include <values.h>
> MAXINT
> HERE
2147483647

The standard solution for big files is to use "long int" although again what exactly that means in practice depends on the compiler etc.

It's not really clear why you are asking about pointers. Pointers by definition work on memory addresses, and the type of the memory address they point to (the number of bytes to use beyond the pointed-to address) is independent of the location in memory.

3

use uint32_t or uint64_t from inttypes.h

It guarantees same size on any platforms.

4

I think, files size could not go beyond the int size. Offset reference type is size_t and it is unsigned int.

5

There's a separate API for file sizes. size_t I believe is meant for sizes of in-memory structures. ftell(3) for example returns a long. lseek(3) returns an off_t. See further <sys/types.h> documentation e.g. <sys/types.h>

The idea that files could not be larger than a particular offset is a source of many bugs and growing pains. Some older file systems could not cope with large files, which back then meant bigger than 2GB or 4GB. We are beginning to see this again as storage capacities are approaching the next boundary. It's the good old "640kb ought to be enough for everybody" syndrome.