Counter controlled loops and while loops

Early exit from loops[ edit ] When using a count-controlled loop to search through a table, it might be desirable to stop searching as soon as the required item is found.

The above while loop is also called a flag-controlled loop. Rao Kosaraju refined the structured program theorem by proving that it is possible to avoid adding additional variables in structured programming, as long as arbitrary-depth, multi-level breaks from loops are allowed.

Numbers that seem "exact" to us in decimal form, such as 0. The While expression is evaluated again. This implies that when a loop terminates correctly, both the exit condition and the loop invariant are satisfied.

Most commonly, in unstructured programming this is jump back up gotowhile in structured programming this is an indefinite loop while loop set to never end, either by omitting the condition or explicitly setting it to true, as while true When this happens, the body of the While loop is not executed again.

The following diagram shows the difference between while and do-while loops. In this section we will learn how to make computer repeat actions either a specified number of times or until some stopping condition is met. Loop system cross-reference table[ edit ] It has been suggested that this article be split into a new article titled Comparison of programming languages control flow.

The time variable is now calculated from a single multiplication and a single addition, which can still introduce some roundoff error, but far less than thousands of additions.

This is know as a busy loop. An early example can be found in Conversional Lisp of Interlisp. Linear - Evaluate the function at the endpoints, and then use a linear interpolation of the endpoint function values in between.

The statement that is being executed within the loop is called the body of the loop.

At that time, the expression is no longer true, the body of the While loop is not executed again, and the execution continues with the statement immediately following the While statement. This process countinues until count contains the value When to Use Which Loop? You will also see occasions where the loop variable is declared as part of the for loop, in C99in which case the variable exists only within the body of the loop, and is no longer valid when the loop completes: Nested Loops The code inside a loop can be any valid C code, including other loops.This web page leads helps to you to master different types of while loops: while loop ; count-controlled loop ; event-controlled loop.

A while loop The syntax of the while loop is: while (Expression) { The counter or the status of the event must be updated within the loop.

If the counter or the status of the event is not updated, the loop. Infinite loops can be implemented using other control flow constructs.

Most commonly, in unstructured programming this is jump back up (goto), while in structured programming this is an indefinite loop (while loop) set to never end, either by omitting the condition or explicitly setting it to true, as while (true).

Demonstrating while loops. These while loops will calculate the factorial of the number 5: ActionScript 3. var # While counter(5) is greater than 0 factorial *= counter # Set new value of factorial to # factorial x counter.

counter. Count-Controlled Repetition. Count-controlled repetition requires control variable (or loop counter) initial value of the control variable increment (or decrement) by which the control variable is modified each iteration through the loop.

There are three different types of Event-Controlled while loops. Sentinel-controlled loops - A sentinel variable is initialized to a specific value. The while loop continues until, through some action inside the loop, the sentinel variable is set to a predefined termination value.

Both while loops and do-while loops (see below) are condition-controlled, meaning that they continue to loop until some condition is met.

Both while and do-while loops alternate between performing actions and testing for the stopping condition.

Counter controlled loops and while loops
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