Program postfix;
uses crt;
const
  maxstack = 100;

type
  basetype = char;
  stack = record
          item : array[1..maxstack] of basetype;
          top  : 0..maxstack;
  end;
var
  i:Byte;
  s:stack;
  str:string;
  operat_0,operat_1:Char;
  underflow,overflow:boolean;
  temporary_number:Byte;
function empty(s:stack):boolean;
begin
 if s.top=0 then empty:=true
            else empty:=false;
end;
procedure pop(var s:stack;var x:basetype;var underflow:boolean);
begin
  if empty(s) then underflow:=true
    else begin
           x:=s.item[s.top];
           s.top :=s.top-1;
           underflow:=false;
         end;
end;
procedure push(var s:stack;x:basetype;var overflow:boolean);
begin
     If s.top>=maxstack then overflow:=true
                        else begin
                               overflow:=false;
                               s.top:=s.top+1;
                               s.item[s.top]:=x;
                             end;
end;
Procedure error_occured;
begin
 writeln ('Ge‡ersiz giriŸ yapld.');
 writeln ('  Sistem halt etti!    ');
 HALT;
end;

begin
textbackground(15);textcolor(0);
repeat
 ClrScr;
 temporary_number:=1;
 s.top:=0;
 write ('Postfix ifadeyi giriniz...:');
 readln(str);
 If length(str)<1 then error_occured;
  For i:=1 to length(str) do
   if not (str[i] in ['a'..'z','A'..'Z','-','+','*','/'])then error_occured;
  for i:=1 to length(str) do
   begin
    if str[i] in ['+','-','*','/'] then
    begin
       pop (s,operat_0,underflow);
       if underflow then error_occured;
       pop (s,operat_1,underflow);
       if underflow then error_occured;
       write ('LD ');
       if operat_1<'A' then writeln ('TEMP_',ord(operat_1))
       else writeln (operat_1);
       case str[i] of
       '+' : write ('ADD ');
       '-' : write ('SUB ');
       '*' : write ('MUL ');
       '/' : write ('DIV ');
     end;
         if operat_0<'A' then writeln ('TEMP_',ord(operat_0))
         else writeln (operat_0);
         push (s,chr(temporary_number),overflow);
         if (overflow) then error_occured;
         writeln ('ST TEMP_',ord(temporary_number));
         temporary_number:=temporary_number+1;
         end
         else begin
         push (s,str[i],overflow);
         if (overflow) then error_occured;
        end;
   end;
 writeln('˜fade de§erlendirildi, kod retildi...');
 writeln('€kmak i‡in X'e , devam i‡in herhangi bir tuŸa basnz.');
until (readKey='X') or (readKey='x');
end.