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Loops

Now that we have our first big feat out of the way, the If statement, we can move on to some basic loops. In many ways, looping is actually easier than the If statement that we just learned. So if you got through that last page okay, you will be just fine from here-on-out! :)

For Loops

The for loop is one of the most often-used loops in VB for games, so we'll start with that. Basically, all that you want it to do is execute a command block a specified number of times. Here is a basic implementation of a simple For loop:

Public Function ExecuteCmdFor(a() As String) As Integer
  Dim i As Integer, b(0) As String
  'i will be our counter, b() is a 'placeholder'
  b(0) = a(1)
  'put the name of the command block to be executed
  'in b()
  For i = 0 To CInt(a(0)) - 1
  'Use vb's built-in for loop to go from 0 to the
  'first parameter, a(0)
    ExecuteCmdExecuteBlock b() 'execute the block!
  Next i
  ExecuteCmdFor = 1
End Function

Simple, huh? Basically, this function becomes a 'wrapper' for vb's native For loop, making life simple on you, the coder. One thing to be noticed, though, is that the command block has no way of knowing the contents of the 'counter' variable, i. Implementing this is something that you should try as an exercise. I would suggest waiting on this, though, until I discuss later possible methods of implementing true, named variables.

Do...Loop Until Loops

This type of loop is also quite simple to implement, again 'wrapping' vb's built-in loop of the same name. Look this code over:

Public Function ExecuteCmdDo(a() As String) As Integer
  Dim b(1) As String, c(0) As String
  'as usual, some placeholder-type arrays
  b(0) = a(1)
  b(1) = a(2)
  'the b() array will be used for getting the flag
  c(0) = a(0)
  'the c() array will be used for calling the command block
  Do 'VB's built-in Do command...
    ExecuteCmdExecuteBlock c() 'execute the command block
  Loop Until CStr(ExecuteCmdGetFlag(b())) = a(3)
  'Loop until bit a(2) of flag a(1) becomes set to a(3) (0 or 1).
  ExecuteCmdDo = 1
End Function

Again, this function should be fairly straightforward. The only 'new' thing is the ability for the script to specify whether to check for the flag being "on" (1) or "off" (0) as the fourth parameter, a(3).

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