CHEAT SHEET (Copy)

 

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1. 🔹 Basic Program Structure

Module Module1
    Sub Main()
        ' Your code goes here
    End Sub
End Module

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2. 🔹 Output to Console

Console.Write("Text")        ' Stays on same line
Console.WriteLine("Text")    ' Moves to next line

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3. 🔹 Input from Console

Dim userInput As String
userInput = Console.ReadLine()

To convert input to numeric types:

Dim number As Integer
number = Convert.ToInt32(Console.ReadLine())

Dim realNumber As Double
realNumber = Convert.ToDouble(Console.ReadLine())

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4. 🔹 Variable Declaration and Data Types

Integer

Dim x As Integer
x = 10

Real (Float/Double)

Dim y As Double
y = 3.14

String

Dim name As String
name = "Alice"

Boolean

Dim flag As Boolean
flag = True

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5. 🔹 Constants

Const PI As Double = 3.14159

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6. 🔹 Operators

Arithmetic:

+   ' Addition  
-   ' Subtraction  
*   ' Multiplication  
/   ' Division (result is Double)  
   ' Integer division  
Mod ' Modulus  
^   ' Power  

Comparison:

=   '<equals>  
<>  '<not equals>  
>   '<greater than>  
<   '<less than>  
>=  '<greater than or equal>  
<=  '<less than or equal>  

Logical:

And  
Or  
Not  

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7. 🔹 Conditional Statements

IF-ELSEIF-ELSE:

If condition Then
    ' statements
ElseIf anotherCondition Then
    ' statements
Else
    ' statements
End If

Nested IF:

If a > 0 Then
    If b > 0 Then
        Console.WriteLine("Both positive")
    End If
End If

SELECT CASE:

Select Case grade
    Case "A"
        Console.WriteLine("Excellent")
    Case "B", "C"
        Console.WriteLine("Good")
    Case Else
        Console.WriteLine("Fail")
End Select

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8. 🔹 Loops

FOR loop:

For i As Integer = 1 To 10
    Console.WriteLine(i)
Next

With step:

For i As Integer = 10 To 1 Step -1
    Console.WriteLine(i)
Next

WHILE loop:

While condition
    ' statements
End While

DO WHILE loop:

Do While condition
    ' statements
Loop

DO UNTIL loop:

Do Until condition
    ' statements
Loop

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9. 🔹 Functions and Procedures

Function with Return:

Function Square(num As Integer) As Integer
    Return num * num
End Function

Sub Procedure (No Return):

Sub Greet(name As String)
    Console.WriteLine("Hello " & name)
End Sub

Calling:

Greet("Hamza")
Dim result As Integer = Square(5)

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10. 🔹 Arrays

1D Array:

Dim numbers(4) As Integer  ' Index from 0 to 4

numbers(0) = 10
Console.WriteLine(numbers(0))

2D Array:

Dim grid(2, 2) As Integer

grid(0, 0) = 5
Console.WriteLine(grid(0, 0))

Loop through 1D array:

For i As Integer = 0 To numbers.Length - 1
    Console.WriteLine(numbers(i))
Next

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11. 🔹 String Manipulation

Dim s As String = "Hello"

s.Length                      ' Returns number of characters  
s.ToUpper()                   ' HELLO  
s.ToLower()                   ' hello  
s.Substring(0, 2)             ' He  
s.IndexOf("e")                ' 1  
s.Contains("el")              ' True  
s = s & " World"              ' Hello World  

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12. 🔹 File Handling (Basic Level)

Writing to File:

My.Computer.FileSystem.WriteAllText("file.txt", "Hello World", False)

Reading from File:

Dim content As String
content = My.Computer.FileSystem.ReadAllText("file.txt")

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13. 🔹 Input Validation Example

Dim age As Integer
Dim valid As Boolean = False

While Not valid
    Console.Write("Enter age: ")
    If Integer.TryParse(Console.ReadLine(), age) Then
        valid = True
    Else
        Console.WriteLine("Invalid input. Try again.")
    End If
End While

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14. 🔹 Error Handling (Basic Try-Catch)

Try
    Dim x As Integer = Convert.ToInt32(Console.ReadLine())
Catch ex As Exception
    Console.WriteLine("Invalid input!")
End Try

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15. 🔹 Comments

' This is a single-line comment

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16. 🔹 Mathematical Functions

Math.Sqrt(25)        ' 5  
Math.Pow(2, 3)       ' 8  
Math.Abs(-10)        ' 10  
Math.Round(3.14159, 2) ' 3.14  

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✅ Exam-Oriented Tips

Concept	Pseudocode	Visual Basic Equivalent
x ← 10	←	x = 10
REPEAT UNTIL loop	Repeat	Do...Loop Until condition
FOR i ← 1 TO N	For loop	For i As Integer = 1 To N
PROCEDURE name()	Procedure	Sub name()
FUNCTION name(): INT	Function	Function name() As Integer
OUTPUT x	Output	Console.WriteLine(x)
INPUT x	Input	x = Console.ReadLine() → Convert as needed

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