Crash Course Delphi, part 2: Forms, Edits,
In this lesson we'll create a simplified version of Foot2Meter,
the application that was introduced in lesson 1.
For now, the accent will not be on what the program does, but
rather on how to start a project, how to save the files, add
components, and so on. But very soon, we'll continue in a higher
- Create a new folder: \DelphiLand\Foot2MeterSimp.
foot2metersimp.zip to \DelphiLand.
- Unzip foot2metersimp.zip to \DelphiLand\Foot2MeterSimp. Check
if you've got the files foot2metersimp.dpr, unit1.dfm and
Starting at the end
How should our simplified Foot2Meter look like and what should it do?
- Open the project Foot2MeterSimp.dpr in Delphi.
- Compile the application. If you have forgotten how to do
that, have a look at lesson 1.
As with every succesful compilation, Delphi will start the
application in the "environment" of the debugger.
Just play around with the program.
- Notice that Delphi gives an error message and that
it pauses the program, if you try to convert an invalid value.
Continue your application. Afterwards you do not get a second
error message, because in this simplified version of
Foot2Meter we are not checking for a valid input (compare this
behaviour with lesson 1).
- Stop the application and quit Delphi.
- Delete all the files from \DelphiLand\Foot2MeterSimp.
Your Turn !
- In the File menu, select New, next select Windows
(Note: in Delphi 7 or older, select New Application)
- Delphi will start a new project:
Unit1 is the name of the unit that goes with Form1. Delphi
created the file Unit1.pas, containing the source code for Form1, the
main form of the application.
- Delphi's title bar shows the name of the new project: Project1.
This means that Delphi created a dproj-file (project file) called
Note: if you start several new projects one after the other during
the same session, the second project gets the name
Project2.dproj, the next one will be Project3,... Delphi
consequently gives names along these lines to new files and new
- Notice the window with the title Form1. That window (form)
is the basis for your project.
Delphi applications for Windows are based on Forms. Every
GUI application has one or more Forms. A Form is a component
in the shape of a window. That's why Bill called it "Windows"...
On the form you put other components, such as Buttons, Edit-boxes,
Radiobuttons, ListBoxes, ComboBoxes and
other well known Windows-creatures.
- You also see the Editor window. That's where the source
code can be viewed and edited. The source code is the result of
the cooperation between Delphi and yourself: for every unit,
Delphi creates a template that you can complete.
For the moment, all these files only exist in the RAM of your computer.
You have to save them to disk files.
- Open the File menu and click Save All.
In the dialog Save Unit1 as, select directory \DelphiLand\Foot2MeterSimp.
Leave Unit1.pas as the file name. The additional data for
Form1, such as the locations and dimensions of the components, are
saved automatically in Unit1.dfm.
- In the next dialog, Save Project1 As, the right directory is
already selected. Enter Foot2MeterSimp as file name. Delphi
saves the program-data of the project as Foot2MeterSimp.dproj
(this file contains the names of the units and the forms that you
created, plus the names of other units used by the project, and so
Files and file naming
It is best to save all files of a new project as soon as possible.
That way, you won't experience nasty surprises as lost projects (what
was that name again?), or an existing project being overwritten by a new
one (and that's a lot worse...)
- You are completely free in naming the first unit (in our case: the
- Of course, all next units of the same project have to be given
- The name of the project file must be different from all unit-names.
In our case, the name Foot2MeterSimp is not allowed for both
the unit and the project, although the file extensions are different!
- Out of the project name, Delphi will create the name for the
compiled executable. In our case this will be Foot2MeterSimp.exe.
Therefore it is worthwile thinking of a suitable name BEFORE starting
Analyzing before you start is half of the game.
Clicking on a button should convert the value in the edit-box from foot
to meter, or from meter to foot.
We know that 1 foot equals 0.3048 meter. Thus it seems that 1 meter
equals 1/0.3048 foot ;)
Components for this application: 1 edit-box for data entry, 2 buttons
(one for Foot -> Meter, one for the reverse), plus a few labels.
Adding the Components
The next steps explain how to add the components to the form:
- Bring the form window to the front. Tip: you also can press function
key F12, which toggles between the code in the editor and the
Probably you will see a raster on the form, facilitating the alignment
of the components. For reasons of clarity I omitted this raster in the
pictures that I show here. On my PC, I switched off the form-raster:
about everything can be personalized in Delphi. But don't change too
much if you only just started with Delphi, because it's quite
complicated to restore the original settings. In the worst case
scenario, you would have to reinstall Delphi :-(
- In the component palette, click on the icon of the TEdit component.
It is on the Standard page of the palette:
- Click somewhere in the form. An Edit-box appears on the form, with
the text Edit1.
- On the form, drag component Edit1 to the upper left-hand corner,
right below the title bar.
- Click the TLabel component from the component palette.
- Move the cursor to somewhere to the right of Edit1 and click: Label1
is placed on the form.
- Add another TLabel to the right of Label1. Label2 is born.
- Add a TButton component (also on the standard page),
somewhere below the Edit-box. A button with the name Button1 appears.
- Below Button1, add a second button to the form.
- Finally, add a TLabel to the right of Button1. By now, your form
should look similar to this:
- Drag the components until Form1 more or less matches the picture
Probably your form is a lot bigger than the one that I show here. Size
the form by dragging the bottom right corner of the window's frame,
just as you would do with any other window.
- Time to save your work: in the File menu, select Save All.
- Let's test. In the Run menu, select Run (or press key F9).
Delphi will compile and run your program.
The program doesn't seem to do anything yet, but make no mistake: this
is a full blown Windows application! You can size and move the window,
enter text in the Edit, click the buttons,...
- Stop the application.
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