assigning a value to a pointer

[ch_dupre]

hello forum,

I'm having some trouble with pointers. First I wanted to have a function that return a pointer but the result was weird. I tried different method, but the results are still incorrect.

Here is a sample code

****************************************************************
int16 data;

int16* returnPtr(void)
{
fprintf(COM2, "address of data: %LX\n", &data);
return &data;
}
void returnPtr2(int16* PTR)
{
PTR = &data;
fprintf(COM2, "address of PTR: %LX\n", PTR);
}
void main()
{
int16* ptr;
int16* localPtr;

ptr = returnPtr();
fprintf(COM2, "address of ptr: %LX\n", ptr);

returnPtr2(ptr);
fprintf(COM2, "address of ptr: %LX\n", ptr);

fprintf(COM2, "address of localPtr: %LX\n", localPtr);
localPtr += 0xFF;
fprintf(COM2, "address of localPtr: %LX\n", localPtr);

localPtr = &data;
fprintf(COM2, "address of data: %LX\n", &data);
fprintf(COM2, "address of localPtr: %LX\n", localPtr);
}
**************************************************************

Here is the output I get:
address of data: 0605
address of ptr: 0005 <<== I would expect 0605 back

address of PTR: 0005 <<== same thing. I expect 0605 here
address of ptr: 0005

address of localPtr: 0005
address of localPtr: 0203 <<==this one makes sense: FF + 5 = 0x203

address of data: 0605
address of localPtr: 0005 <<== again, I expect 0x0605.

Am I doing something wrong? Or is there a limitation in the compiler.


I've tried using compile V3.249 and V4.013

Thanks,

Christophe

[PCM programmer]

The true address for 'data' is 0006. I compiled your program for an
18F452, and then looked at the Symbol Table. It shows that 0006 is the
address.

I think printf is very buggy for displaying the address of a variable.
To fix the problem, I had to cast the '&data' value to an int16, as shown
in bold below. I tested this with PCH vs. 3.249.