Pointers in BBC BASIC (on RISC OS)

I finally managed to get it working... so this is a quick note to myself, in case I forgot. I intend to use it mainly 
to get some kind of structures working, since BBC BASIC on RISC OS doesn't have structs (unlike windows version...). 
Basically will reserve a zone of memory and divide it according the needs. Maybe (surely) exists a better method, 
but this is how I thought it right now.

For example, let's say we want to reserve a zone of memory in which we'll store an integer and a pointer to a string. 
Thus, we'll need 32 bit for the integer (4 bytes) and another 4 bytes for the pointer. [I have yet to check the size 
of the pointer var, but I think 4 bytes is ok]

So, we'll reserve 2 bytes of memory for this mememory block. Also we reserve 10 bytes for a string of 10 chars.

`    DIM mb% 7` -> bytes 0 through 7<br>
`    DIM sb% 9`

Now we'll allocate values:

`    !mb% = 1234`<br>
`    $sb% = "Chars str."`

The `!` is used for integers indirection and `$` for string indirection (also for bytes indirection). `!mb%` 
references the first byte in memory block, which is an integer represented on 32 bits. `$sb%` references the starting 
address of the string [`$(sb%+1)` references the second byte = the second character of the string and so on]

Now, on the second byte of our memory block we'll put the address of the string:

`    !(mb%+4) = sb%`

For testing the results, we'll have to display something on the screen:

`    PRINT "At address ";mb%;" we have an integer: ";!mb%`<br>
`    PRINT "At address ";mb%+4;" we have the string address: ";!(mb%+4)`<br>
`    PRINT "At address ";\!(mb%+4);" we have the string: ";%(!(mb%+4))`

All seems ok now; will try to experiment more and find some more info about the subject.

Note: For floating point indirection, the '|' symbol is used. For BBC BASIC V, 5 bytes are used and for BBC BASIC VI, 
8 bytes are used.

tags: RISC-OS, programming, pointers