Language Reference

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=x+1; 
    end; 
    print x;                 /* x=101 */