Data commit

Task/Soloways-recurring-rainfall/Delphi/soloways-recurring-rainfall.delphi

@@ -0,0 +1,156 @@
+{This code would normally be in a library somewhere, but it is included here for clarity}
+
+{TKeywaiter interface}
+
+type TKeyWaiter = class(TObject)
+ private
+  FControl: TWinControl;
+  FControlCAbort: boolean;
+ protected
+  procedure HandleKeyPress(Sender: TObject; var Key: Char);
+ public
+  KeyChar: Char;
+  ValidKey: boolean;
+  AbortWait: boolean;
+  constructor Create(Control: TWinControl);
+  function WaitForKey: char;
+  function WaitForInteger: integer;
+  function WaitForReal: double;
+  property ControlCAbort: boolean read FControlCAbort write FControlCAbort;
+ end;
+
+
+{ TMemoWaiter implementation }
+
+type TControlHack = class(TWinControl) end;
+
+constructor TKeyWaiter.Create(Control: TWinControl);
+{Save the control we want to wait on}
+begin
+FControl:=Control;
+FControlCAbort:=False;
+end;
+
+procedure TKeyWaiter.HandleKeyPress(Sender: TObject; var Key: Char);
+{Handle captured key press}
+begin
+KeyChar:=Key;
+ValidKey:=True;
+if ControlCAbort then AbortWait:=KeyChar = #$03;
+end;
+
+
+function TKeyWaiter.WaitForKey: char;
+{Capture keypress event and wait for key press control}
+{Spends most of its time sleep and aborts if the user}
+{sets the abort flag or the program terminates}
+begin
+ValidKey:=False;
+AbortWait:=False;
+TControlHack(FControl).OnKeyPress:=HandleKeyPress;
+repeat
+	begin
+	Application.ProcessMessages;
+	Sleep(100);
+	end
+until ValidKey or Application.Terminated or AbortWait;
+Result:=KeyChar;
+end;
+
+
+function TKeyWaiter.WaitForInteger: integer;
+var C: char;
+var S: string;
+begin
+Result:=0;
+S:='';
+{Wait for first numeric characters}
+repeat
+	begin
+	C:=WaitForKey;
+	if AbortWait or Application.Terminated then exit;
+	end
+until C in ['+','-','0'..'9'];
+{Read characters and convert to}
+{integer until non-integer arrives}
+repeat
+	begin
+	S:=S+C;
+	C:=WaitForKey;
+	if AbortWait or Application.Terminated then exit;
+	end
+until not (C in  ['+','-','0'..'9']);
+Result:=StrToInt(S);
+end;
+
+
+type TCharSet = set of char;
+
+function TKeyWaiter.WaitForReal: double;
+var C: char;
+var S: string;
+const RealSet: TCharSet = ['-','+','.','0'..'9'];
+begin
+Result:=0;
+S:='';
+{Wait for first numeric characters}
+repeat
+	begin
+	C:=WaitForKey;
+	if AbortWait or Application.Terminated then exit;
+	end
+until C in RealSet;
+{Read characters and convert to}
+{integer until non-integer arrives}
+repeat
+	begin
+	S:=S+C;
+	C:=WaitForKey;
+	if AbortWait or Application.Terminated then exit;
+	end
+until not (C in RealSet);
+Result:=StrToFloat(S);
+end;
+
+
+
+{===========================================================}
+
+
+function WaitForReal(Memo: TMemo; Prompt: string): double;
+{Wait for double entered into TMemo component}
+var KW: TKeyWaiter;
+begin
+{Use custom object to wait for and capture reals}
+KW:=TKeyWaiter.Create(Memo);
+try
+Memo.Lines.Add(Prompt);
+Memo.SelStart:=Memo.SelStart-1;
+Memo.SetFocus;
+Result:=KW.WaitForReal;
+finally KW.Free; end;
+end;
+
+var Count: integer;
+var Average: double;
+
+procedure RecurringRainfall(Memo: TMemo);
+var D: double;
+begin
+Count:=0;
+Average:=0;
+while true do
+	begin
+	D:=WaitForReal(Memo,'Enter integer rainfall (99999 to quit): ');
+	if Application.Terminated then exit;
+	if (Trunc(D)<>D) or (D<0) then
+		begin
+		Memo.Lines.Add('Must be integer >=0');
+		continue;
+		end;
+	if D=99999 then break;
+	Inc(Count);
+	Average := Average + (1 / Count) * D - (1 / Count)*Average;
+	Memo.Lines.Add('New Average: '+FloatToStrF(Average,ffFixed,18,2));
+	end;
+end;