11.61 while

while <condition> [ loopname <loopname> ]

The while command executes a block of commands repeatedly, checking the provided condition at the start of each iteration. If the condition is true, the loop executes again. This is similar to a do loop, except that the contents of a while loop may not be executed at all if the iteration criterion tests false upon the first iteration. For example, the following code prints out the low-valued Fibonacci numbers:

i = 1
j = 1
while (j < 50)
  print j
  i = i + j
  print i
  j = j + i