Introduction to Delphi Grade 10

Delphi is a visual programming environment — you design the screen AND write the code. You drag components onto a form to build the interface, then write Delphi code to make it all work. This page covers the IDE layout, components, naming, events, and your first program.

The Delphi IDE — What You See When You Open It

When you open Delphi, this is what you will see. It might look overwhelming at first — but each area has one clear job:

Delphi 11 — Design View (this is where you build the form your user will see)

Object Inspector — set properties like Name, Caption, Color

Tool Palette — drag components from here onto the form

Switching to Code View

Press F12 to toggle between the Design View (what you see above) and the Code View (where you type your Delphi code).

Code View — this is the Delphi code structure that is automatically created for you

The Delphi IDE Layout

An Integrated Development Environment (IDE) is a software application that combines the tools a programmer needs — a code editor, a compiler, and a debugger — into a single interface, so you can design, write, test and run a program without switching between separate tools.

Key IDE Panels

Objects, Classes & Components

Delphi is an Object-Oriented Programming (OOP) language, so almost everything you place on a form is an object. To talk about objects precisely, three related terms are used:

Every object has:

• Attributes — what it looks like and contains, described through its properties and events.
• Behaviour — what it can do, described through its methods.

Basic Format of Statements

An assignment statement stores a value in a property or variable using the assignment operator :=. We use code in Delphi to assign values to properties of components in the following format:

Component.Property := Value;

All the properties a component has can be seen in the Object Inspector when that component is selected — the same properties you set visually at design time can also be set in code.

Form1.Height := 500;
Form1.Width := 700;
Button1.Caption := 'Register';
Shape1.Top := 20;
Shape1.Left := 20;

Step-by-Step: Creating Your First Project

1. File → New → Windows VCL Application — creates a blank Form (TForm).
2. Place components by clicking them in the Tool Palette, then clicking on the form.
3. Set properties in the Object Inspector (e.g. change a button's Caption).
4. Double-click a button to go to Code View and write the event handler.
5. File → Save All (Ctrl+Shift+S) — save in a NEW dedicated folder.
6. Press F9 to compile and run.

The Files Delphi Creates

Delphi creates several files for every program, but you only ever need to save two of them yourself — Delphi regenerates the rest automatically when you run the program.

Visual Component Reference

Components are the building blocks placed on a form. Each is an object with properties and events. Here is what the most common ones look like:

Naming Convention

Every component gets a prefix that indicates its type, followed by a meaningful name. This makes code readable.

Accelerator (Hot) Keys

Placing an & in front of a letter in a component's Caption underlines that letter and turns it into a keyboard shortcut. Pressing Alt + that letter clicks the component without using the mouse.

btnRed.Caption := '&Red';   // underlines the R — press Alt+R to click the button

Event-Driven Programming

Delphi programs are event-driven — code only runs when something HAPPENS (an event), like pressing a button, typing in a box, or a timer ticking.

How to Create an Event Handler

1. In Design View, double-click a button to create its OnClick handler automatically.
2. For other events, go to the Events tab in the Object Inspector and double-click next to the event name.
3. Delphi creates a skeleton procedure. Write your code between begin and end.
4. Never change the procedure header — only add code inside.

procedure TForm1.btnCalculateClick(Sender: TObject);
begin
  // Your code goes here
  ShowMessage('Button clicked!');
end;

ShowMessage and InputBox

ShowMessage displays a pop-up with a message. InputBox pops up a window asking the user to type something. Both are modal — the program pauses until the user responds.

ShowMessage('Hello world!');
ShowMessage('Result: ' + IntToStr(iAnswer));

// Returns a string
sName   := InputBox('Name', 'Enter your name:', '');

// Convert to integer
iNum    := StrToInt(InputBox('Number', 'Enter a number:', ''));

// Convert to real
rAmount := StrToFloat(InputBox('Amount', 'Enter amount:', ''));

// Get first character only
cClass  := InputBox('Class', 'Enter class:', '')[1];

Components — Properties

Properties control how a component looks and behaves. Set them in the Object Inspector or through code.

More Properties in Code

The same Component.Property := Value; format works for every property, including nested ones like Font.Color:

Label1.Font.Color   := clGreen;
Shape1.Brush.Color  := clRed;

Methods

Methods are pre-written operations that perform tasks on components. Format: ComponentName.Method;

Syntax Rules