CHAPTER 14: Blocks and Statements

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14.10 The while Statement

The while statement executes an Expression and a Statement repeatedly until the value of the Expression is false .

WhileStatement:

	while ( Expression ) Statement

WhileStatementNoShortIf:

	while ( Expression ) StatementNoShortIf

The Expression must have type boolean , or a compile-time error occurs.

A while statement is executed by first evaluating the Expression. If evaluation of the Expression completes abruptly for some reason, the while statement completes abruptly for the same reason. Otherwise, execution continues by making a choice based on the resulting value:

• If the value is true , then the contained Statement is executed. Then there is a choice:
  • If execution of the Statement completes normally, then the entire while statement is executed again, beginning by re-evaluating the Expression.
  • If execution of the Statement completes abruptly, see S14.10.1 below.
• If the value of the Expression is false , no further action is taken and the while statement completes normally.

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

14.10.1 Abrupt Completion

Abrupt completion of the contained Statement is handled in the following manner:

• If execution of the Statement completes abruptly because of a break with no label, no further action is taken and the while statement completes normally.
  • If execution of the Statement completes abruptly because of a continue with no label, then the entire while statement is executed again.
  • If execution of the Statement completes abruptly because of a continue with label L, then there is a choice:
    • If the while statement has label L, then the entire while statement is executed again.
    • If the while statement does not have label L, the while statement completes abruptly because of a continue with label L.
  • If execution of the Statement completes abruptly for any other reason, the while statement completes abruptly for the same reason. Note that the case of abrupt completion because of a break with a label is handled by the general rule for labeled statements (S14.6).