Search results
Results from the WOW.Com Content Network
Sometimes within the body of a loop there is a desire to skip the remainder of the loop body and continue with the next iteration of the loop. Some languages provide a statement such as continue (most languages), skip, [8] cycle (Fortran), or next (Perl and Ruby), which will do this. The effect is to prematurely terminate the innermost loop ...
Common among these are the break and continue statements found in C and its derivatives. The break statement causes the innermost loop to be terminated immediately when executed. The continue statement will move at once to the next iteration without further progress through the loop body for the current iteration.
These are analogous to the use of a return statement in non-terminal position – not strictly structured, due to early exit, but a mild relaxation of the strictures of structured programming. In C, break and continue allow one to terminate a loop or continue to the next iteration, without requiring an extra while or if statement. In some ...
a continue not contained within a nested iteration statement is the same as goto cont. The break statement is used to end a for loop, while loop, do loop, or switch statement. Control passes to the statement following the terminated statement. A function returns to its caller by the return statement.
The most common statement is an expression statement, consisting of an expression to be evaluated, followed by a semicolon; as a side effect of the evaluation, functions may be called and variables assigned new values. To modify the normal sequential execution of statements, C provides several control-flow statements identified by reserved ...
The loop control keywords are treated as expressions in Perl, not as statements like in C or Java. The next keyword jumps directly to the end of the current iteration of the loop. This usually causes the next iteration of the loop to be started, but the continue block and loop condition are evaluated first.
/* precondition: x 2 = 0 */ LOOP x 1 DO x 0 := 0; LOOP x 2 DO x 0 := x 0 + 1 END; x 2 := x 2 + 1 END. This program can be used as a subroutine in other LOOP programs. The LOOP syntax can be extended with the following statement, equivalent to calling the above as a subroutine: x 0 := x 1 ∸ 1 Remark: Again one has to mind the side effects.
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.