Supporting Activity: Iteration and Repetition Structures

An iteration structure is a process where a set of algorithms of the program is repeated a specified numbers of times or until a particular result is achieved, we can call these action loops. There are three parts that make up a loop such as loop termination, body of the loop and transfer back to the start of the loop. There are two kinds of loops post-test loop and pre-test loop. Loop Termination determines when, based on the condition the loop will be stopped.

The body of the loop is where the program or algorithms that will repeat within the loop. Transfer back to start of the loop gives control to the beginning of the loop, so that the iteration can begin. Pre-test loops test condition happens before the body of the loop and post-test loop test condition happens after the body of the loop is executed.

A problem that repetition structures solve is that it lets the programmer use one set of instruction within the body of the loop to run over and over again until a specific condition is met. It lets the programmer simplify the list of algorithm or program without having to write the same list of instruction repeat itself as another loop.
Below is an example program of a repetition structure process loop.

Declare Number As Integer
Repeat
Write “ Please enter a number: “ Input Number Write Number
Until Number == 0
Write “List Ended”

Drake, E., & Venit, S. (2011).

Drake, E., & Venit, S. (2011). Prelude to programming: Concepts and design (5th ed.). Boston, MA: Addison-Wesley