REPEAT..UNTIL (author: Tao Yue, state: unchanged)
The posttest loop has the following format:
repeat statement1; statement2 until BooleanExpression;
In a repeat loop, compound statements are built-in -- you don't need to use begin-end. Also, the loop continues until the Boolean expression is TRUE, whereas the while loop continues until the Boolean expression is FALSE.
This loop is called a posttest loop because the condition is tested after the body of the loop executes. The REPEAT loop is useful when you want the loop to execute at least once, no matter what the starting value of the Boolean expression is.