DO...[EXIT DO]... LOOP

Description:

DO and LOOP cause code to be executed while a certain condition evaluates to true, or until a certain condition evaluates to true. The "while" and "until" parts of this expression can be located either in the "DO" statement or the "LOOP" statement. The following form is good for cases when you want a loop that always executes once and then only loops back as long as a condition is met. It will continue looping back and executing the code as long as the booleanExpr evaluates to true. To jump out of a DO LOOP construction before the conditions are met, use EXIT DO

  'execute the code inside this loop at least once
  do
    'code in here
  loop while booleanExpr

You can also use the UNTIL keyword to reverse the logic of the expression:

  'execute the code inside this loop at least once
  do
    'code in here
  loop until booleanExpr

Usage:

  'examples using "loop while" and "loop until"
  print "print a zero"
  do
    print a
    a = a + 1
  loop while a > 10
  print
  print "print 1 to 9"
  do
    print a
    a = a + 1
  loop while a < 10
  print
  'examples using loop until
  print "print a zero"
  do
    print b
    b = b + 1
  loop until b = 1
  print
  print "print 1 to 9"
  do
    print b
    b = b + 1
  loop until b = 10
  'examples using loop while
  print "print 1 to 3"
  a = 1
  do while a <= 3
    print a
    a = a + 1
  loop
  print
  print "print 9 to 7"
  b = 9
  do until b = 6
    print b
    b = b - 1
  loop
  print
  print "don't print anything"
  do while c = 10
    print c
    c = c + 1
  loop
  'example using EXIT DO
  do while i < 100
    i = i + 4
    print i
    if i > 13 then exit do
  loop
  end