Language Reference

DO Statement with an UNTIL Clause

DO UNTIL (expression);

DO variable = start TO stop <BY increment> UNTIL(expression);

The DO UNTIL statement conditionally executes statements iteratively.

The arguments to the DO UNTIL statement are as follows:

expression: is an expression that is evaluated at the bottom of the loop for being true or false.
variable: is the name of a variable that indexes the loop.
start: is the starting value for the looping variable.
stop: is the stopping value for the looping variable.
increment: is an increment value.

Using an UNTIL expression enables you to conditionally execute a set of statements iteratively. The UNTIL expression is evaluated at the bottom of the loop, and the statements inside the loop are executed repeatedly as long as the expression yields a zero or missing value. In the following example, the body of the loop executes until the value of X exceeds 100:

x = 1;
do until (x>100);
   x = x + 1;
end;
print x;

Figure 24.110: Result of a DO-UNTIL Statement

x
101