DO Statement with an UNTIL Clause

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DO Statement with an UNTIL Clause

conditionally executes statements iteratively

DO UNTIL( expression);

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

The inputs 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 indexing 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 makes possible the conditional execution of 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 example that follows, the body of the loop executes until the value of X exceeds 100:

   x=1;
   do until (x>100);
      x+1;
   end;
   print x;                 /* x=101 */

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