The do statement executes a Statement and an Expression repeatedly until the
value of the Expression is false.
DoStatement:
doStatementwhile (Expression) ;
The Expression must have type boolean, or a compile-time error occurs.
A do statement is executed by first executing the Statement. Then there is a choice:
do statement completes abruptly for the same reason. Otherwise, there is a choice based on the resulting value:
true, then the entire do statement is executed again.
false, no further action is taken and the do statement completes normally.
Executing a do statement always executes the contained Statement at least once.