A.9.5 Iteration Statements
Iteration statements specify looping.
- iteration-statement:
- while (expression) statement do statement while (expression); for (expressionopt; expressionopt; expressionopt) statement
In the while and do statements, the substatement is executed repeatedly so long as the value of the expression remains unequal to 0; the expression must have arithmetic or pointer type. With while, the test, including all side effects from the expression, occurs before each execution of the statement; with do, the test follows each iteration.
In the for statement, the first expression is evaluated once, and thus specifies initialization for the loop. There is no restriction on its type. The second expression must have arithmetic or pointer type; it is evaluated before each iteration, and if it becomes equal to 0, the for is terminated. The third expression is evaluated after each iteration, and thus specifies a re-initialization for the loop. There is no restriction on its type. Side-effects from each expression are completed immediately after its evaluation. If the substatement does not contain continue, a statement
- for (expression1; expression2; expression3) statement
is equivalent to
expression1; while (expression2) {
- statement expression3;
}
Any of the three expressions may be dropped. A missing second expression makes the implied test equivalent to testing a non-zero element.