Introduction
to Visual Basic

Basic Operations

Making Decisions

Repeating Code

Common Syntax

What do you want to do?

Syntax Examples

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Clearing a ListBox

ListBox1.Items.Clear Clears the contents of a ListBox

Creating a Comment

'Comment - use an apostrophe at the begriming of the line. The computer will ignore whatever comes after it on the same line. It should appear as green.

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Declaring Variables - Do this at the very top of the program just below Public Class Form1().

Dim Number as Integer. - Creates a variable called Number that stores whole numbers, so that values like 3.33, 104.75 are stored as 3 and 104.
Dim Number as Decimal - Creates a variable called Number that can hold decimal numbers, so that values like 3.33 and 104.75 are stored as 3.33 and 104.75.
Dim aString as String - Creates a variable called aString that can store text.

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Grabbing the contents from a TextBox and placing in a variable

Number = TextBox1.Text, Name = TextBox1.Text
Takes the contents of TextBox1 (numbers or text) and stores in a variable.

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Using Input Boxes

Name = InputBox("What is your Name?") - Displays a box with a question. What the user then enters is stored in a variable called Name.

Using Message Boxes

MesgBox("You entered " & Name) - Displays a box with a statement and the contents of the variable called Name.

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Loops - repeats a number actions. There are different types of Loops.

For... Next Loops - repeats instructions a set number of times. It looks like this
For counter = 1 to 10
ListBox1.Items.Add(message)
Next
If the variable message holds the text "I Like Computing" then this loop will be printed out in the ListBox 10 times.

Do ... While Loop - will repeat instructions until a condition is met. For example:-
Do While counter <10
counter +=1
Loop
Will keep adding 1 to a variable called counter as long as the counter is less than 10.

Do .. Until Loop - similar to the previous example. Will keep repeating until a condition is met.
Do Until Number = 10
Number +=1
Loop
Will keep adding 1 to a variable called Number Until it equals 10.

Adding Items to a ListBox.

ListBox1.Items.Add("The answer is " & answer) - Displayed the listbox with the text "The answer is " with the contents of the Variable called answer

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Creating Objects.

Find the object you want, Label, ListBox, Command button, TextBox in the Tool sidebar and drag onto your form. Rearrange them to your liking.

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Setting a string variable to empty.

Dim Name as string - sets up a string variable.
Name = String.Empty - clears or sets the Name variable to empty.

Creating a subroutine.

Simples. Just write the name you wish to use in the main program with round brackets Eg. Get_Scores() and then use as part of declaration of the sub routine. eg
Private Sub Get_Scores()
score1 = TextBox1.Text
End Sub

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Introduction to Visual Basic

Basic Operations

Making Decisions

Repeating Code

Common Syntax

A

Introduction
to Visual Basic