Exit

From REALbasicWiki

Exit is a control statement that ends execution of a loop or method. Exit can take certain keyword parameters that allow more precise control over what is exited.

Contents 1 Exit 2 Exit [For|Do|While] 3 Exit For loopVariable 4 Exit [Sub|Function] 5 Exit outside a loop

[edit] Exit

Calling Exit with no parameters causes execution to jump out of the innermost loop block containing it to the next statement. Here is a simple example.

Function IndexOf(theList as Object, theObject as Object)
  dim theIndex as Integer = -1
  for i as Integer = 0 to UBound(theList)
    if theList(i) is theObject then
      theIndex = i
      exit
    end if
  next
  return theIndex
End Function

If a match is found, exit causes execution to jump to the next statement following the loop, return theIndex.

[edit] Exit [For|Do|While]

You can pass one of the keywords For, Do, or While as a parameter. This tells Exit to jump out of the innermost For|Do|While block containing it. In the example that follows, the statement exit do jumps out of the do loop containing it.

  do
    while true
      exit do
    wend
  loop

[edit] Exit For loopVariable

In the presence of nested for loops, you can pass an additional parameter, the loop variable, to Exit For to indicate which For-Next loop you intend to exit. Here is the canonical example.

for x as Integer = 0 to lastX
  for y as Integer = 0 to lastY
    if someCondition then
      exit for x
    end if
  next
next

This also works for For Each loops, and the loop variable need not be a numeric datatype. I contrive an example.

 dim theList() as FolderItem
 theList.Append DesktopFolder
 
 for each foo as FolderItem in theList
   for i as Integer = 0 to 10
     exit for foo
   next
 next

[edit] Exit [Sub|Function]

Passing one of the keywords Sub or Function means that control will jump to the end of the method. The compiler requires that you call Exit Sub only within a subroutine, and Exit Function within a function. This is almost the same behavior as Return, except that one cannot return a value. It is unclear why this option is even available.

[edit] Exit outside a loop

Beware that if Exit is not contained within a For-Next, While-Wend, or Do-Loop looping block, its execution will cause control to jump to the end of the method, similar to calling Exit Sub or Exit Function. Here is an example.

 Sub Example()
 if true then
   exit
 end if

 MsgBox "Msgbox"
End Sub

Here, the MsgBox statement is skipped because Exit causes control to jump to the end of the method. If the method is a function, then the default value will be returned.