Mega Code Archive
Numberlinedistance
<![CDATA[
unit NumUnit;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls;
const
InitialValue = 1000000;
MaxNumStrLength = 255;
type
TMainForm = class(TForm)
Label1: TLabel;
Label2: TLabel;
Label3: TLabel;
Label4: TLabel;
Label5: TLabel;
Label6: TLabel;
Label7: TLabel;
Edit1: TEdit;
Edit2: TEdit;
GetResultButton1: TButton;
Edit3: TEdit;
Label8: TLabel;
Label9: TLabel;
Edit4: TEdit;
Edit5: TEdit;
GetResultButton2: TButton;
Edit6: TEdit;
ExitButton: TButton;
Label10: TLabel;
Label11: TLabel;
Label12: TLabel;
Label13: TLabel;
Label14: TLabel;
Label15: TLabel;
Label16: TLabel;
Label17: TLabel;
Label18: TLabel;
procedure ExitButtonClick(Sender: TObject);
procedure GetResultButton1Click(Sender: TObject);
procedure GetResultButton2Click(Sender: TObject);
private
//private declarations
function NumberLineDistReal(valOne, valTwo: Real): Real;
function NumberLineDistInteger(valOne, valTwo: Integer): Integer;
function IsConvertibleToInt(convStr: String): Boolean;
function IsConvertibleToFloat(convStr: String): Boolean;
public
//public declarations
end;
var
MainForm: TMainForm;
implementation
{$R *.DFM}
////////////////////////////////////////////////////
procedure TMainForm.ExitButtonClick(Sender: TObject);
begin
Close;
end;
//////////////////////////////////////////////////////////
procedure TMainForm.GetResultButton1Click(Sender: TObject);
var
edit1Int: Integer;
edit2Int: Integer;
numLineDist: Integer;
tempString: String;
begin
if ((IsConvertibleToInt(Edit1.Text) = True) and
(IsConvertibleToInt(Edit2.Text) = True)) then
begin
edit1Int := StrToInt(Edit1.Text);
edit2Int := StrToInt(Edit2.Text);
numLineDist := NumberLineDistInteger(edit1Int, edit2Int);
Edit3.Text := IntToStr(numLineDist);
end
else
begin
tempString := 'Please input only valid integer values';
Application.MessageBox(PChar(tempString), ' Invalid Input Value', mb_OK);
end;
end;
//////////////////////////////////////////////////////////
procedure TMainForm.GetResultButton2Click(Sender: TObject);
var
edit4Real: Real;
edit5Real: Real;
numLineDist: Real;
tempString: String;
begin
if ((IsConvertibleToFloat(Edit4.Text) = True) and
(IsConvertibleToFloat(Edit5.Text) = True)) then
begin
edit4Real := StrToFloat(Edit4.Text);
edit5Real := StrToFloat(Edit5.Text);
numLineDist := NumberLineDistReal(edit4Real, edit5Real);
Edit6.Text := FloatToStrF(numLineDist, ffGeneral, 5, 5);
end
else
begin
tempString := 'Please input only valid decimal values';
Application.MessageBox(PChar(tempString), ' Invalid Input Value', mb_OK);
end;
end;
/////////////////////////////////////////////////////////////////
function TMainForm.NumberLineDistReal(valOne, valTwo: Real): Real;
//UTILITY FUNCTION
//simple arithmetic operations of the kind that you do all the time
//in graphics can produce erroneous outputs if one is not extremely
//careful about 'abs-ing' values where appropriate: this function
//bundles up the algorithm to find the 'absolute distance along the
//number line' between two Real values so that we can just call it
//up as appropriate...
begin
Result := InitialValue;
if ((valOne >= 0) and (valTwo >= 0)) then
begin
if (valOne >= valTwo) then Result := (valOne - valTwo)
else Result := (valTwo - valOne);
end;
if ((valOne < 0) and (valTwo >= 0)) then
begin
if (valOne >= valTwo) then Result := (abs(valOne) + valTwo)
else Result := (abs(valOne) + valTwo);
end;
if ((valOne >= 0) and (valTwo < 0)) then
begin
if (valOne >= valTwo) then Result := (valOne + abs(valTwo))
else Result := (abs(valTwo) + valOne);
end;
if ((valOne < 0) and (valTwo < 0)) then
begin
if (valOne >= valTwo) then Result := (abs(valTwo) - abs(valOne))
else Result := (abs(valOne) - abs(valTwo));
end;
end;
//////////////////////////////////////////////////////////////////////////
function TMainForm.NumberLineDistInteger(valOne, valTwo: Integer): Integer;
//UTILITY FUNCTION
//see notes in NumberLineDistReal() above...
begin
Result := InitialValue;
if ((valOne >= 0) and (valTwo >= 0)) then
begin
if (valOne >= valTwo) then Result := (valOne - valTwo)
else Result := (valTwo - valOne);
end;
if ((valOne < 0) and (valTwo >= 0)) then
begin
if (valOne >= valTwo) then Result := (abs(valOne) + valTwo)
else Result := (abs(valOne) + valTwo);
end;
if ((valOne >= 0) and (valTwo < 0)) then
begin
if (valOne >= valTwo) then Result := (valOne + abs(valTwo))
else Result := (abs(valTwo) + valOne);
end;
if ((valOne < 0) and (valTwo < 0)) then
begin
if (valOne >= valTwo) then Result := (abs(valTwo) - abs(valOne))
else Result := (abs(valOne) - abs(valTwo));
end;
end;
///////////////////////////////////////////////////////////////
function TMainForm.IsConvertibleToInt(convStr: String): Boolean;
{a general purpose function to test whether a string CAN be converted
to an integer value. Useful to avoid EConvertError exceptions and also
useful to have in a program when coding and testing to avoid the
possibility of the program hanging on you...}
type
TDigChrs = set of Char;
var
tempArray: array[0..MaxNumStrLength] of Char;
idx: Integer;
lineLength: Integer;
validIntStr: Boolean;
digitChars: TDigChrs;
begin
digitChars := ['0'..'9'];
validIntStr := True;
digitChars := digitChars + ['-'];
lineLength := Length(convStr);
//copy the line into an array and
//test each character as you go...
for idx := 0 to (lineLength - 1) do
begin
tempArray[idx] := convStr[idx + 1];
if (not(tempArray[idx] in digitChars)) then validIntStr := False;
if (idx >= MaxNumStrLength) then break;
end;
if (lineLength = 0) then validIntStr := False;
Result := validIntStr;
end;
/////////////////////////////////////////////////////////////////
function TMainForm.IsConvertibleToFloat(convStr: String): Boolean;
{a general purpose function to test whether a string CAN be converted
to a floating point value. Useful to avoid EConvertError exceptions and
also useful to have in a program when coding and testing to avoid the
possibility of the program hanging on you...}
type
TDigChrs = set of Char;
var
tempArray: array[0..MaxNumStrLength] of Char;
idx: Integer;
lineLength: Integer;
validFloatStr: Boolean;
digitChars: TDigChrs;
begin
digitChars := ['0'..'9'];
validFloatStr := True;
digitChars := digitChars + ['-', '.'];
lineLength := Length(convStr);
{copy the line into an array and test each character as you go...}
for idx := 0 to (lineLength - 1) do
begin
tempArray[idx] := convStr[idx + 1];
if (not(tempArray[idx] in digitChars)) then validFloatStr := False;
if (idx >= MaxNumStrLength) then break;
end;
if (lineLength = 0) then validFloatStr := False;
Result := validFloatStr;
end;
end.
]]>