There are three types of loop for us to cover with VB.NET: a For loop, a Do loop, and a While … End While loop. This last one is almost the same as a Do loop, and we won’t be covering it here. But the other two types of loop come in very handy, and a lot of the time you can’t programme effectively without using loops.

What is a Loop?

A loop is something that goes round and round and round. If someone told you to move your finger around in a loop, you’d know what to do immediately. In programming, loops go round and round and round, too. In fact, they go round and round until you tell them to stop. You can programme without using loops. But it’s an awful lot easier with them. Consider this.

You want to add up the numbers 1 to 4: 1 + 2 + 3 + 4. You could do it like this

Dim answer As Integer

answer = 1 + 2 + 3 + 4

MsgBox answer

Fairly simple, you think. And not much code, either. But what if you wanted to add up a thousand numbers? Are you really going to type them all out like that? It’s an awful lot of typing. A loop would make life a lot simpler.

But don’t get hung up too much on the name of the Loop. Just remember what they do: go round and round until you tell them to stop.

We’ll discuss the For Loop first.

Popularity: unranked

Part 1 – If statements

Start a new project. Add a textbox, a Label and a button to your new Form. Then write a programme that does the following:

1. Asks users to enter a number between 10 and 20.
2. The number will be entered into the Textbox.
3. When the Button is clicked, your Visual Basic code will check the number entered in the Textbox.
4. If it is between 10 and 20, then a message will be displayed.
5. The message box will display the number from the Textbox.
6. If the number entered is not between 10 and 20 then the user will be invited to try again, and whatever was entered in the Textbox will be erased

Part 2 – Select Case Statements

Add a Combo box and another button to your form. Create a list of items for your Combo Box. The list of items in your Combo box can be anything you like – pop groups, football teams, favourite foods, anything of your choice. Then try the following:

Use a select case statement to test what a user has chosen from your drop-down list. Give the user a suitable message when the button was clicked.

In the next section of this course, we’ll move on to loops in Visual Basic .NET.

Popularity: 9%

Popularity: 68%