A high-level programming language structure that repeats instructions based on the results of a comparison. In a DO WHILE loop, the instructions within the loop are performed if the comparison is true. In a DO UNTIL loop, the instructions are bypassed if the comparison is true. The following DO WHILE loop prints 1 through 10 and stops.

   counter = 0
   do while counter < 10
     counter = counter + 1
     ? counter
   enddo