#include <iostream.h>

#define q = 3

int n;
if (n < 0) return 0;

for (n=1; n <= q; n++)
{
double f = 1;
{f *= n;}
}

#include <iostream> // let's try to use a compiler from this millenium
 
int main()
{
int n, result = 1, value = 3;
for ( n = 1; n <= value; n++ )
{
	 result *= n;
}
std::cout << value << "! = " << result << std::endl;
std::cin.get(); // pause ???
return 0;
}
 
/* my output
3! = 6
*/

int main()
{
int num;
do{
cout << "Enter a number between 1 and 10";
cin>>num;
}while( num < 1 || num > 10 ); /* ask some more if we dont get something between 1 and 10 */
double factorial( num );
for( int n(num-1) ; n > 0 ; factorial *= n, --n); /* demonstration of how the for loop can be extremely useful */
cout << "The factorial of "<< num << " is "<< factorial << endl;
}

{---------------------------------------------------------------------
 PROGRAM: FACTORIAL2.PAS
 Version:				   Turbo Pascal 6.0
 -------------------------------------------------------------------}
PROGRAM Factrl2 (Input, Output);
USES
  Crt;
CONST
  MaxM  =  7;
VAR
  Choice,
  M			:  Integer;
  UserQuits	:  BOOLEAN;
{------------------------------------}
{			PROCEDURES			  }
{------------------------------------}
{-----------------------------}
{		  INIT.PROC		  }
{-----------------------------}
PROCEDURE Init;
BEGIN
  TextBackground(Blue);				   { Sets colors					 }
  TextColor(White);
  Window(0,0,80,25);
  ClrScr;
END;
 
{-----------------------------}
{		 .PROC		   }
{-----------------------------}
PROCEDURE Null;
BEGIN
END;
{-----------------------------}
{	  FACTFORDO .PROC		}
{-----------------------------}
PROCEDURE FactForDo;
VAR
  k,								   { index }
  FAC,
  Factorial		 :  INTEGER;		{ partial factorial }
BEGIN
  ClrScr;
  WriteLn;
  Write(' ':20,' Enter an integer - 0 to ',MaxM,': ');
  ReadLn(M);
  IF M <= MaxM THEN
	BEGIN
	  FAC := 1;
	  FOR k := 2 to M DO
		FAC := FAC * K;
	  Factorial := FAC;
	  WriteLn;
	  WriteLn(' ':20,'		  M was entered as: ', M );
	  WriteLn;
	  WriteLn(' ':20,'	   M!, or M Factorial = ', Factorial );
	END
	ELSE
	  BEGIN
		WriteLn;
		WriteLn('The number you entered is greater than ',MaxM,'.  Re-enter. ');
	  END;  { ELSE }
  WriteLn;
  WriteLn(' Press <ENTER> to return to menu.');
  ReadLn;
END;	  {FactForDo}
 
{-----------------------------}
{	  FACTORIAL.PROC		 }
{-----------------------------}
FUNCTION Factorial ( M : Integer ) : Integer;
BEGIN
  IF M = 0 THEN
	Factorial := 1
  ELSE
	Factorial := M * Factorial( M-1 );
END;	  { Factorial }
 
{-----------------------------}
{		FACTREC.PROC		 }
{-----------------------------}
PROCEDURE FactRec;
BEGIN
  ClrScr;
  WriteLn;
  Write(' ':20,'Enter an integer - 0 to ',MaxM,': ');
  ReadLn(M);
  WriteLn;
  IF M > MaxM THEN
	WriteLn('The number you entered is greater than ',MaxM,'.  Re-enter. ')
	ELSE
	  BEGIN
		WriteLn;
		WriteLn(' ':20,'		  M was entered as: ', M );
		M := Factorial( M );
	  END;  { ELSE }
  WriteLn;
  WriteLn(' ':20,'	   M!, or M Factorial = ', M );
  WriteLn;
  WriteLn(' Press <ENTER> to return to menu.');
  ReadLn;
END;	  {FactRec}
 
{------------------------------------}
{		   MAIN PROGRAM			 }
{------------------------------------}
BEGIN
  Init;
  UserQuits := False;
  REPEAT
	ClrScr;
	WriteLn;
	WriteLn(' ':25, ' Menu For Factorial Methods ' );
	WriteLn;
	WriteLn(' ':20, ' 1.  Factorial Using a FOR DO Loop' );
	WriteLn(' ':20, ' 2.  Factorial Using Recursion'	 );
	WriteLn(' ':20, ' 3.  Quit '						 );
	ReadLn ( Choice );
	CASE Choice OF
	   1  :  FactForDo;
	   2  :  FactRec;
	   3  :  UserQuits := True;
	END;
  UNTIL UserQuits;
END.