3) Programming Fundamentals (Step by Step)

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This section is intentionally detailed. Read each concept, then run the example. Learning is faster when you test small pieces one by one.

Step 1: Understand Values and Types

A program works with values. A type tells LunarBasic what kind of value each variable can hold.

• Integer: whole numbers (0, -5, 42).
• Float/Double: decimal numbers (1.5, 3.14159).
• Boolean: True or False.
• String: text inside quotes ("Hello").

Dim score As Integer
Dim speed As Float
Dim isAlive As Boolean
Dim playerName As String

score = 10
speed = 2.5
isAlive = True
playerName = "Luna"

Step 2: Learn Assignment

Assignment stores a value in a variable.

Dim health As Integer
health = 100
health = health - 25

After the second assignment, health becomes 75.

Step 3: Use Expressions and Math

Dim total As Integer
Dim base As Integer
Dim bonus As Integer

base = 50
bonus = 20
total = (base + bonus) * 2

Expressions can combine numbers, variables, and operators.

Step 4: Make Decisions with If

Dim score As Integer
score = 85

If score >= 100 Then
    DebugPrint("Perfect")
ElseIf score >= 60 Then
    DebugPrint("Pass")
Else
    DebugPrint("Try again")
End If

Step 5: Repeat Work with Loops

For Loop

Dim i As Integer
For i = 1 To 5
    DebugPrint("Count: " + Str(i))
Next

While Loop

Dim x As Integer
x = 0

While x < 3
    DebugPrint("x=" + Str(x))
    x = x + 1
Wend

Step 6: Organize Code with Subs and Functions

Sub performs work. Function performs work and returns a value.

Sub PrintGreeting(name As String)
    DebugPrint("Hello, " + name)
End Sub

Function Add(a As Integer, b As Integer) As Integer
    Return a + b
End Function

Dim result As Integer
PrintGreeting("Luna")
result = Add(3, 4)

Step 7: Store Multiple Values with Arrays

Dim points(5) As Integer

points[0] = 10
points[1] = 20
points[2] = 30

DebugPrint("First point: " + Str(points[0]))

Step 8: Use Strings for User-Facing Text

Dim firstName As String
Dim message As String

firstName = "Ari"
message = "Welcome, " + firstName
DebugPrint(message)

Step 9: Build a Tiny Complete Program

SetAppTitle("Fundamentals Demo")
Graphics(800, 600, False)
SetClsColor(12, 18, 28)

Dim running As Boolean
Dim fontRef As Integer
Dim x As Integer

fontRef = LoadFont("", 20)
running = True
x = 50

Do
    If KeyDown(KEY_RIGHT) Then x = x + 3
    If KeyDown(KEY_LEFT) Then x = x - 3

    Cls()
    DrawText(fontRef, x, 40, "Move with LEFT/RIGHT. ESC exits.")
    Flip()

    If KeyHit(KEY_ESC) Then
        running = False
    End If
Loop Until Not running

FreeFont(fontRef)

Common Beginner Mistakes (and Fixes)

• Mistake: using a variable before assigning it. Fix: initialize variables early.
• Mistake: forgetting End If, Next, or Wend. Fix: write closing lines immediately.
• Mistake: putting expensive setup inside the frame loop. Fix: load once before the loop, free after the loop.
• Mistake: changing many things before testing. Fix: test after each small change.

Deep Reference Pages

• Names and Values
• Variables, Constants, and Assignment
• Control Flow
• Functions, Subs, and Return
• Arrays
• Expressions

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