Atari ST GFA basic : what do variable suffixes correspond to?

Question

I'm dusting off my Atari ST 520, and am trying to understand some semantic details of the GFA basic. The TYPE(ptr) function is documented this way :

     Determines the type of the variable at which a pointer
       is set.

       'ptr' is an integer expression (usually *var).
       TYPE(ptr) returns a code according to the type of
       variable to which 'ptr' is pointing.
           0=var  
           1=var$  
           2=var%  
           3=var!  
           4=var()  
           5=var$()
           6=var%()  
           7=var!()

The same documentation does not talk about what these suffixes mean. (It must be so obvious)

I seem to recall that $ is a string/memory block, % an integer, () an array of the same. What are ! and nothing? ! seems to be used for 0/1 variables.

Guardhouse

Answer 1

That's correct $ string, % integer, ! boolean , and nothing (0) is double.

http://www.atari-forum.com/wiki/index.php?title=GFAvariablestutorial

Voluptuous

Answer 2

The final version of the manual states:

Boolean  !  1 byte (1 bit in arrays)  0 or -1 (FALSE or TRUE)
Byte     |  1 byte                    0 to 255
Word     &  2 bytes                   -32768 to 32767
Long     %  4 bytes                   -2147483648 to 2147483647
Float    #  8 bytes                   2.225073858507E-308 to 3.595386269725E+308
String   $  0 to 32767 bytes          ASCII value 0 to 255 for each character

The default variable type doesn't display a suffix and can be changed.

Fret

Thank you for your answer. I see that the list you provided includes # for Float. What is the documentation for TYPE(ptr), in the same version of the manual? – Guardhouse

Answer 3

TYPE(ptr) returns a code according to
the type of variable to which 'ptr' is pointing.

GFA BASIC v2.xx

code	meaning	suffix		bits
-1	error occured
0	real		max. 1.0E+154	48
1	string	$	max. 32767 characters
2	long	%	[-2147483648,2147483647]	32
3	boolean	!	[-1,0]	16
4	real array	()
5	string array	$()
6	long array	%()
7	boolean array	!()		1

GFA BASIC v3.xx

code	meaning	suffix		bits
-1	error occured
0	real	#	max. 3.595386269725E+308	64
1	string	$	max. 32767 characters
2	long	%	[-2147483648,2147483647]	32
3	boolean	!	[-1,0]	16
4	real array	()
5	string array	$()
6	long array	%()
7	boolean array	!()		1
8	card	&	[-32768,32767]	16
9	byte	l	[0,255]	8
10
11
12	card array	&()
13	byte array	l()
14
15

Without a suffix the type defaults to real but this also depends on any DEFBIT (!), DEFBYT(|), DEFFLT(#), DEFINT(%), DEFSTR($), or DEFWRD (&) that could be active.

Until I can find a solution I will represent the byte symbol "|" as "l" in the above table.

Remake