Do Loop

DO [WHILE|UNTIL condition1]
   [loop body]
LOOP [WHILE|UNTIL condition2]

A DO LOOP allows you to specify that an application should repeat an statement or set of statements while some condition remains true and/or until another condition is true.

In the above syntax, both condition1 and condition2 are optional, but the use of at least one of them is encouraged for clarity.

The loop body consists of zero or more statements.

Eventually, the condition(s) should become false. At this point, the repetition terminates, and the first statement after the DO LOOP executes.

Note that if your DO LOOP condition is never false, your DO LOOP may repeat infinitely. In this case, the program stays stuck in RUN mode.

Examples

For example, the loop below will print 3, then double the 3 to 6 and print it, then double the 6 to 12 and print it, and so on until the variable becomes greater than 100. At this point the repetition stops.

00010 let a=3
00020 do until a > 100
00030    print a
00040    let a = 2 * a
00050 loop

You can reach an identical result by using WHILE and reversing the condition from a > 100 to a <= 100:

00010 let a=3
00020 do while a <= 100
00030    print a
00040    let a = 2 * a
00050 loop

You may want to combine the use of both WHILE and UNTIL in the same DO LOOP in order to separate two unrelated conditions