14.12.2 Iteration

Next, a for iteration step is performed, as follows:

• If the Expression is present, it is evaluated, and if evaluation of the Expression completes abruptly, the for statement completes abruptly for the same reason. Otherwise, there is then a choice based on the presence or absence of the Expression and the resulting value if the Expression is present:
  • If the Expression is not present, or it is present and the value resulting from its evaluation is true, then the contained Statement is executed. Then there is a choice:
    • If execution of the Statement completes normally, then the following two steps are performed in sequence:
      • First, if the ForUpdate part is present, the expressions are evaluated in sequence from left to right; their values, if any, are discarded. If evaluation of any expression completes abruptly for some reason, the for statement completes abruptly for the same reason; any ForUpdate statement expressions to the right of the one that completed abruptly are not evaluated. If the ForUpdate part is not present, no action is taken.
      • Second, another for iteration step is performed.
    • If execution of the Statement completes abruptly, see §14.12.3 below.
  • If the Expression is present and the value resulting from its evaluation is false, no further action is taken and the for statement completes normally.

If the value of the Expression is false the first time it is evaluated, then the Statement is not executed.

If the Expression is not present, then the only way a for statement can complete normally is by use of a break statement.