Conditional Loops

Conditional loops provide the ability to run a block of code through a loop when the number of loop iterations are not known until run time.  There are three different types of conditional loops that provide their own unique features for different circumstances.

While. The While loop allows you to execute a block of code while the specified express holds true.  The following example increments a variable by 1 while it is less than a 1000:

Number = 2

While Number < 1000

Number = Number + 1

Wend

MsgBox number

Note that the keyword Wend is used to mark the end of a While loop.

Do While. A feature with a standard While loop is that if its expression is false to begin with, then the loop will never execute. However, if you require for the loop to execute at least once (even if the conditional expression is false), then use a Do While loop as such:

Number = 1000

Do

'although the expression is already false,
'the loop will still execute once
Number = Number + 1

Loop While Number < 1000

MsgBox Number

Do Until. A Do Until loop behaves the same way as a Do While loop, except that instead of running while the conditional expression is true it will run until the expression is true. The following demonstrates this:

Number = 1

Do

Number = Number + 1

Loop Until Number > 1000

MsgBox Number