fibonacci.pas

program recurseFibonacci;
Uses sysutils;

const
   MAXFIB  = 47;
   VERSION = 0.1;
   
var
   i, f, n : longint;
   TS	   : TTimeStamp;
   t	   : array [0..50] of longint;
   DONE	   : Boolean;
   QUIET   : Boolean;
   VERBOSE : Boolean;
   TIMING  : Boolean;
   NUMSET  : Boolean;
   code	   : word;

function fibonacci(n :  longint): longint;
begin
   (* Return -1 when invalid *)
   if (n>47) or (n<1) then
      fibonacci := -1
   else if n=1 then
      fibonacci := 0
   else if n=2 then
      fibonacci := 1
   else
      fibonacci := fibonacci(n-1) + fibonacci(n-2);
end;

procedure Usage;
Begin
   writeln('Fibonacci - Prints the nth number in the Fibonacci sequence.');
   writeln('Michael J. Chappell   January 2, 2019');
   writeln;
   writeln('Usage is:');
   writeln;
   writeln('    fibonacci [-h][-q][-t][-v][n]');
   writeln;
   writeln('-h  Prints this help message.');
   writeln('-q  Quiet.  Prints the result.');
   writeln('-t  Prints timing information.');
   writeln('-v  Prints information from intermediate computations.');
   writeln;
   writeln('n   Should be an integer between 1 and 47.');
   writeln;
   writeln('You will be prompted for ''n'' if it is not provided.');
   writeln;
   writeln('fibonacci version ', VERSION:3:1,
	   '  Copyright January 2, 2019  Michael J. Chappell');
   writeln;
End;

begin
   QUIET := False;
   VERBOSE := False;
   TIMING := False;
   NUMSET := False;
   DONE := False;
   for i:=0 to argc-1 do
      begin
	 if AnsiCompareStr(argv[i],'-q')=0 then QUIET := TRUE;
	 if AnsiCompareStr(argv[i],'-t')=0 then TIMING := TRUE;
	 if AnsiCompareStr(argv[i],'-v')=0 then VERBOSE := TRUE;
	 if AnsiCompareStr(argv[i],'-h')=0 then DONE := True;
	 val(argv[i],n,code);
	 if code=0 then
	    begin
	       NUMSET := True;
	    end;
      end; { for }
   if NOT (TIMING or VERBOSE) then QUIET := True;
   if VERBOSE then QUIET := False;
   if (NOT NUMSET) and (NOT DONE) then
   begin
      writeln('How many numbers in the fibonacci sequence should be output?');
      readln(n);
   end; { if }
   if (n>MAXFIB) or (n<1) then DONE := TRUE;
   if (n>0) and (NOT DONE) then
      begin
	 if VERBOSE then
	    writeln('The first ', n, ' numbers in the Fibonacci sequence are:');
	 TS := DateTimeToTimeStamp(Now);
	 t[0] := TS.time;
	 for i:= 1 to n do
	    begin
	       f := Fibonacci(i);
	       if f<0 then Usage;
	       if NOT QUIET then
		  begin
		     if TIMING or VERBOSE then
			write('Fibonacci(',i:2,') = ',f:11, '.  ');
		     TS := DateTimeToTimeStamp(Now);
		     t[i] := TS.time;
		     if TIMING then
			writeln('The computation took ',(t[i] - t[i-1]):5,
				' milliseconds.')
		     else writeln;
		  end { if NOT QUIET }
		  else
		  begin
		     if (i=n) then writeln(f);
		  end;
	    end { for }
      end; { if n>0 and NOT DONE }
   if DONE then Usage();
end.
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Friday, 4 July 2025 Michael J. Chappell Contact me at: mcsuper5@freeshell.org
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