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My first Delphi Application - calculator

I have just downloaded Delphi 7 and I want to learn how to build my first application. I installed it using the "Typical" option for components. I have some Perl experience but this is my first with the Delphi program. The application is a calculator that will estimate the weight in carats of a gemstone cut from a particular type of rough in various designs. There is an online version of what I want to do written in Perl found at http://www.amfed.org/faceters/faqs_gem_weight.shtml

The formula for the application is Weight = (Vol./W^3) x (specific gravity) x (width3) / 200.

The "Vol./W^3" will already be known by the user as it it generated by another design program. The value of "Vol./W^3" will be between 0.000 and 1.000.

The specific gravity will be selected from a dropdown list. The stone names and their specific gravity values can be found at http://www.fishhead.com/sg-values.txt . Note that the values of specific gravity may have a range in value so the calculation of the weight will need to also show a range in weight.

The next value of width (in millimeters) will be entered by the user and that value needs to be cubed.

The last calculation is to divide by 200.

What I want is a window with input boxes like the online link above but I don't need the "Notes" box. Under that have a "Calculate" and "Clear Form" button. Under that I need an output text box where the calculation is displayed. Use the online link above and enter .241 and 12mm to see the output calculation.

I'm starting this out at 500 points because what I need is a step by step tutorial as well as code. I'll be happy to award additional points to anyone adding additional tweaks that will improve the final product or more points to any one expert who gives me the complete package. I'm not sure how to exceed the 500 point limit but we can figure that out I'm sure. Please include suggestions on background colors, heading bar, etc...

Roza

Hi Gary!

Ok. How would I do it:

Put following objects on a form and set its names as following:
Object - Name
TEdit - VolFactor
TEdit - Width
TComboBox - Material
TButton - Calculate
TButton - ClearForm
TEdit - Result

Ok. I would have specific gravity in file like this:
Create file called Material.ifo in directory where you will save your project to.
---bof
13
achroite (tourmaline),3.03,3.10
actinolite,3.00,3.44
adamite,4.32,4.48
alexandrite (chrysoberyl),3.75
albite,2.62
almandine (garnet),4.10,4.30
amber,1.10
amblygonite,3.00,3.10
amethyst (quartz),2.66
ametrine (quartz),2.66
analcime,2.27
anatase,3.90
andalusite,3.13,3.16
--eof

first line is presenting number of materials in file then next lines name and mingrafity then maxgravity.

Ok.. let's go back to project.

Then create structure representing file:
Go to unit1 and insert following declaration between
uses
Windows, Messages....
and
type

type TMaterial=RECORD
Name: STRING[30];
GravityFrom, GravityTo: real;
END;

Roza

it would look like:

uses
Windows, Messages...

type TMaterial=RECORD
Name: STRING[30];
GravityFrom, GravityTo: real;
END;

type TForm1=class(TForm)...

Then add to private declarations:
private
{ Private declarations }
MaterialInfo: ARRAY OF TMaterial;

Ok.. now let's load info from file to our array:

Duble click on a form to create OnFormCreate event:
procedure TForm1.FormCreate(Sender: TObject);
VAR F: textfile;
Line: STRING;
Materials, i: INTEGER;
begin
DecimalSeparator:='.'; //usual separator is , but we have . in file so we changa it
AssignFile(F, 'material.ifo');
Reset(F); //open file
ReadLn(F,Materials); //Read number of materials
Setlength(MaterialInfo,Materials);
FOR i:=0 TO Materials-1 DO //read materials to our array
BEGIN
ReadLn(F,Line);
MaterialInfo[i].Name:=Copy(Line,1,Pos(',',Line)-1);
Delete(Line,1,Pos(',',Line));
IF Pos(',',Line)>0 THEN
BEGIN
MaterialInfo[i].GravityFrom:=StrToFloat(Copy(Line,1,Pos(',',Line)-1));
Delete(Line,1,Pos(',',Line));
MaterialInfo[i].GravityTo:=StrToFloat(Line);
END
ELSE
BEGIN
MaterialInfo[i].GravityFrom:=StrToFloat(Line);
MaterialInfo[i].GravityTo:=0;
END;
Material.Items.Add(MaterialInfo[i].Name); //add material name to Material ComboBox
END;
CloseFile(F); //Close input file
end;

Then duble click on Calculate button to set on Click event:

procedure TForm1.CalculateClick(Sender: TObject);
VAR res, res2: real;
begin
res2:=0;
res:=StrToFloat(Width.Text);
res:=res*res*res;
res:=res*StrToFloat(VolFactor.Text);
res:=res/200;
if MaterialInfo[Material.ItemIndex].GravityTo>0 THEN
res2:=res*MaterialInfo[Material.ItemIndex].GravityTo;
res:=res*MaterialInfo[Material.ItemIndex].GravityFrom;
Result.Text:=FloatToStr(res);
IF Res2>0 THEN Result.Text:=Result.Text+' - '+ FloatToStr(res2);
end;

procedure TForm1.ClearFormClick(Sender: TObject);
begin
VolFactor.Text:='0';
Width.Text:='0';
Result.Text:='0';
end;

You can also select material name by Material.ItemIndex:= and number.

Ok.. I think this is it. If you would like any aditional explanation or something more in your project then just ask.

Roza