Showing posts with label Iteration. Show all posts
Showing posts with label Iteration. Show all posts

Wednesday, October 27, 2010

The For loop

The For loop is used when the number of repetitions is known. It uses a single variable to start the loop, and indicates how many times the loop needs to execute.

For intCount = 0 To 5
   msgbox("This is loop number " & intCount)

Next


The loop counter variable in this instance is intCount. It begins at 0. Each pass of the loop causes the loop counter to increment +1. The loop will execute 6 time - from 0 to 6.

What is a loop?

Loops allows a programmer to repeat a block of code a number of times while some condition is true, or until some condition becomes true. For instance, a loop could be used to prompt a user for an answer until the correct input is entered.

A loop must contain a starting condition and an ending condition. It is very important that a loop is able to reach an ending condition or we end up with what what is called an ‘infinite loop’ – a loop that never ends. This can cause our programs to behave abnormally and may even cause a computer to ‘crash’.