Fibonacci Numbers with Turbo Pascal 3.

[CP/M User]

Hello,

I've stumbled across an unusual problem with this following program while using Turbo Pascal 3:

program fibonacci;

function fib(n:integer): integer;
begin
    if (n <= 2) then
        fib := 1
    else
        fib := fib(n-1) + fib(n-2);
end;

var
    i:integer;

begin
    for i := 1 to 16 do
        write(fib(i), ', ');
    writeln('...');
end.

The problem being the correct sequence of numbers isn't being produced. It's starts fine with 1, 1, but then it counts up to 15. The code is on Progopedia and includes Turbo Pascal 3 as part of the compilers which can compile. I'm using the CP/M version which has been tweaked for the Amstrad CPC computers, so I'm assuming it works correctly for the 16bit versions, but don't know if other CP/M versions of TP3 are struggling with this?

 

[gertk]

This I found on the web:

CP/M-80 version only: Because of the way local variables
are handled during recursion, a variable local to a
subprogram must not be passed as a var-parameter in
recursive calls.

There is more info at:

https://groups.google.com/forum/#!topic/net.lang.pascal/ifEsKpb6Pqo

 

[CP/M User]

Thanks for that, it's a wonder I haven't come across that limitation earlier.