can anybody please explain how I can pass procedures
or functions as parameters to another function in Pascal?
You may also send a sample application that does this.

Thanx,

Dirk

  {declare the function you want to pass as a data type }
   type
      myfunc = function (input: Integer): integer;
   end;

  {declare another function which uses your first function as a variable}
   function usefunc(input:integer):integer; FAR;

  {implement it like so}
  function usefunc(input:integer):integer; FAR;
     begin
            {do something}
     end;

 {You can now use your function as a variable like so}
     return := usefunc(myfunc);

If the function you're passing is in a a DLL, you'll have to EXPORT it.

TYPE
        TrigFunc = Function ( Rad : Real ) : Real;

Procedure UseTrig ( Msg : String, Trig : TrigFunc );

  Begin { UseTrig }
        WriteLn ('Trig function ', Msg, ' result ', Trig(0.23));
  End;  { UseTrig }

Procedure UseTrig ( Msg : String, Trig : TrigFunc );

  Begin { UseTrig }
        WriteLn ('Trig function ', Msg, ' result ', Trig(0.23));
  End;  { UseTrig }

{
 the function is represented by a  far  pointer. This means you have to
 alternatively:
  a) do an $F+
  b) declare the function in the INTERFACE section
  c) declare the function forwards.

var f:TrigFunc;
begin
     f:=tan;
     UseTrig('tan',f);    
end.

--
Peter Sch"afer

"office":
schae...@malaga.math.uni-augsburg.de
http://wwwhoppe.math.uni-augsburg.de/schaefer

Just follow the bouncing code

Potions copywrite 1996 Nuclear Waste Software all rights reseverved

function Figtriangle (base,height:real):real;
{local variables to the function}
{**********************************
accepts the base and hieght of the triangle and performs the
calculations of finding the surface area
***********************************}
begin
       figtriangle := half * base * height;{basic formula for the area
                                      of a triangle}
end;{function}

function figcircle (area,radius:real):real;{local variables to the
function}
{*************************************
accepts the input of the radius to calculate the surface area of a
circle
******************************}
begin
      figcircle := Pi * (sqr(radius));{basic formula for the surface
area
                                       of a circle}
end;{function}

Function figtrap (top,base,height:real):real;
{variables local to the function}
{************************************
Accepts the input of the base, the top and the height of the trapezoid
to calculate the surface area...
*********************************}
begin
      figtrap := half*(base+top)*height
      {formula for the area of a trapezoid}
end;{function}

Procedure Display_menu;
{***************************************
Purpose display the menu of options...
****************************************}
Begin

 Writeln (' The options that are avaiable to you are ');{menu}
 Writeln (' "0" to exit the program.');                 {menu}
 Writeln (' "1" To obtain the surface area of a Triangle. '); {menu}
 Writeln (' "2" To obtain the surface area of a Circle. ');   {menu}
 Writeln (' "3" To obtain the surface area of a Trapezoid. ');{menu}
 End;{display_menu procedure}

 procedure triangle
{********************************
Computes the surface area of a triangle
input/output...
*********************************};
Begin

 Writeln ('Please enter the base length and the height of the
triangle');
{displays to the screen}
 Readln (base, height);{reads the variable input}
 write ('The surface area is ',figtriangle(base,height):7:2);
 {writes the computations to the screen}
 Writeln ( ' units.');{display to the screen}
 writeln;{blank line}
 display_menu {calls the procedure variable display_menu}

End; {end procedure triangle}

Procedure circle
{******************************
Calculates the suface area of a circle
input/output
*******************************};
Begin
Writeln ('Please enter the radius of the circle.');{prompt user for
input}
readln (radius);                                   {reads input}
write ('The surface area is ',figcircle(pi,radius):7:2);
                                            {displays to the screen}
Writeln;                                    {blank line}
display_menu                                {calls the display_menu}
end; {end procedure}

procedure trap
{*******************************
Calculates the surface area of a trapezoid
input/output
********************************};
Begin
Writeln ('Please enter the lengths of the base, the top and ');
{prompt the user for input}
Writeln ('the height of the trapezoid you wish to find the');
{displays to screen}
writeln ('              surface area of.');{display to the screen}
readln (base, top, height );                {reads input}
write ('The surface area is ',figtrap (base,top,height):7:2);
{displays to the screen}
Writeln; {blank screen}
display_menu {calls the display_menu procedure}
end;{procedure}

Begin
 {******************************MAIN PROGRAM*********************}

     Writeln; {displays a blank line}
     Writeln ('         Nuclear Waste Software Presents, ');{Header}
     Writeln ('                  the home                  ');
     Writeln  ('           Surface Area Computer!  ');{header}
     Writeln ; {displays a blank line}
     Writeln ('                        _ _ /a     Ack Pffft
Thwerrp!!');
     {my logo}
     Writeln ('                       \ o.O |
');
     {my logo}
     Writeln ('                       =(___)=
');
     {my logo}
     Writeln ('                          U
');
     {my logo}
     Writeln; {blank line}
     Display_menu;
     Writeln ('Please enter your option');{prompts the user for input}
     Writeln; {blank line}
     readln (option); {reads input of the option}
     while option <> 0 do
     begin
     if option = 1 then
     triangle
     else if option = 2 then
     circle
     else if option = 3 then
     trap
     else
     writeln ('Warning! Invalid option, please re-enter your
option.');
     writeln;
     readln (option);
     end; {while}