quit.w=0 : i.w=0
While i < 5 AND quit=0
    If i=4
        NPrint "Quitting loop..."
        quit=1
    Else
        NPrint "Counting... ", i
    EndIf
    i+1
Wend

; And just to show the same thing with a different loop type
i=0 : quit=0
Repeat
    If i=4
        NPrint "Quitting loop..."
        quit=1
    Else
        NPrint "Counting... ", i
    EndIf
    i+1
Until i=10 OR quit=1

MouseWait
End