Free Pascal 2.0.4

Version of implementation Free Pascal of programming language Pascal

Bugfix release.

Examples:

Factorial - Pascal (44):

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.

Hello, World! - Pascal (57):

program helloworld;

begin
    writeln('Hello, World!');
end.

Fibonacci numbers - Pascal (58):

This example uses recursive definition of Fibonacci numbers.

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.

Factorial - Pascal (96):

This example is exactly the same as main recursive example for Pascal implementations, except for that it uses real data type to store factorial values. Command writeln(f:-1:0) outputs the floating point number f with 0 digits after decimal point and left-justifies it.

program factorial;

function fact(n: integer): real;
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):-1:0);
end.

Quadratic equation - Pascal (178):

Pascal has built-in complex data type complex, but using it is inconvenient in this case, because writeln can’t output complex numbers directly, and functions Re and Im would have to be used. In this example calculations are done in real numbers. Library function halt (added in Extended Pascal) exits current block (in later versions it is replaced with exit).

program Quadratic;

var
   A,B,C,D: integer;

begin
   write('A = ');
   readln(A);
   if (A=0) then
   begin
      writeln('Not a quadratic equation.');
      halt;
   end;
   write('B = ');
   readln(B);
   write('C = ');
   readln(C);
   D := B*B-4*A*C;
   if (D=0) then
   begin
      writeln('x = ',-B/2.0/A);
      halt;
   end;
   if (D>0) then
   begin
      writeln('x1 = ',(-B+Sqrt(D))/2.0/A);
      writeln('x2 = ',(-B-Sqrt(D))/2.0/A);
   end
   else
   begin
      writeln('x1 = (',-B/2.0/A,',',Sqrt(-D)/2.0/A,')');
      writeln('x2 = (',-B/2.0/A,',',-Sqrt(-D)/2.0/A,')');
   end;
end.