In C language I can easily print a variable's address just by using the & operator.
int x = 100;
printf("Value of x: %d\n", x
); printf("Address of x: %p\n", &x
);
you can code the above _almost_ exactly the same in FPC under Windows using NTDLL's sprintf.
basically, instead of a printf call, use sprintf(yourcharbuffer, <same stuff as printf>) with @x instead of &x followed by a writeln(yourcharbuffer);
The only thing you have to be aware of is that NTDLL's sprintf doesn't have support for floating point types e.g, %f, %g, etc. For those you can use msvcrt.dll (which will often be included in the process anyway because a fair number of Windows dll use it - IOW, you can often use it "for free")
Also, NTDLL includes about a third, maybe even a half, of the C runtime library which is often convenient but, it's important to know the differences (they are some very important ones, as well as some, now well known, bugs.)
HTH.