Loops
Loops repeat codes. For example if you need to determine if Word.exe was loaded when your program was running, you would use a loop because Word could be run at any time, so therefore we would need to search (or loop continuously) for it until the program was opened (whether 1 minute or 30). There a few kinds of Loops you will learn in this tutorial...
Do While LoopsThis loop is probably the most commonly used loop that VB supports. The Do While loop works w/ comparison operators, such as VB's If statement does. It uses comparison operators such as <>, =, <, >, etc... After that, you would throw in some codes... And once you finish the loop you would write "Loop," just as you would write "End If" at the end of the If statement.
Do While Comparison
VB Codes
Loop
The Do While Loop continues looping if the comparison test is true, once its false, it stops. You must however make sure that all loops you have in your program finish properly, b/c if the loop doesn't finish properly, you might not be able to close your program. A never ending Loop is called an Infinite Loop.
Example
Private Sub Command1_Click()
Dim AgeInput As Integer Dimming is the proper way to code
age = MsgBox("You must be older than 18", vbQuestion + vbSystemModal + vbYesNo, "Age")
If age = 7 Then If 7 (No button) was pressed then close
End the program b/c user isn't old enough
Else
The user is old enough they pressed 6, which is the yes button
AgeInput = InputBox("How old are you?", "Age")User is entering age
End If
Do While AgeInput < 18 if the users less then 18
MsgBox "You aren't old enough", vbCritical, "Error"
telling them
AgeInput = InputBox("How old are you?", "Age")
asking them again
and this loop will continue until the user
writes an integer 18 or higher!
Loop
End Sub
Do While TheSum < 1000
TheSum = TheSum + 1
Loop
The Do Until Loop runs the code as long as the comparison test is false.
Do Until Comparison
VB Codes
Loop
Do Until Password = Password2
Msgbox "The passwords do not match!", vbCritical
Loop
There are other Do Loops also.
Here is the format for them:
Do
VB Codes
Loop While Comparison
Do
VB Codes
Loop Until Comparison
For A = 1 To 10
Beep
Next A
This simply beeps 10 times b/c it's counting from 1 to 10. You can also write "For A = 1 To 10 Step 2" which can count up to 10 by 2's... By the way in order to terminate loops early, the "Exit For" & "Exit Do" do just that, find an example here. Now you are ready to move on to some other important things...
