Factorial in Pascal

Example for versions Free Pascal 2.0.4, Free Pascal 2.2.0, Turbo Pascal 4.0, Turbo Pascal 5.0, Turbo Pascal 5.5, Turbo Pascal 6.0, Turbo Pascal 7.0, gpc 20070904

This example uses recursive factorial definition.

Note that this example works in all given implementations of Pascal, but it produces slightly different results. In gpc everything works perfectly. Turbo Pascal and Free Pascal have arithmetic overflow for factorial of numbers greater than 12, but Free Pascal reports an error:

13! = Runtime error 215 at $004013C7
$004013C7
$00401449
$004063E0

while Turbo Pascal doesn’t detect the error and simply prints wrong values:

13! = 1932053504
14! = 1278945280
15! = 2004310016
16! = 2004189184

This example doesn’t work in Turbo Pascal 3.0 and earlier due to absence of longint data type in these versions.

In GNU Pascal this program works without any problems. 

program factorial;

function fact(n: integer): longint;
begin
    if (n = 0) then
        fact := 1
    else
        fact := n * fact(n - 1);
end;

var
    n: integer;

begin
    for n := 0 to 16 do
        writeln(n, '! = ', fact(n));
end.