FIT100: Fluency With Information
Technology
Lab 10 Iteration Exercises
Reference
This lab assumes you are familiar with Chapter 20, “Once Is
Not Enough” of FIT
Goal
The goal of this lab is to practice writing iteration statements
and become familiar with how the for-statement works. We will also place images, which should be helpful on Project 2.
Preparation
Review the main features of the for-statement from Chapter
20, including the details of the World Famous Iteration.
Also, set up a web page in which to practice your JavaScript
statements. The page should have the usual HTML plus the JavaScript tags in it.
Exercises
- Declare
an iteration variable (most programmers will pick i and that is what the
examples assume). Write a loop that iterates 5 times, repeating the
statement:
document.write("The iteration variable
"
+
"has the value " + i + "<br>");
If the loop’s initialization sets i
to 0 and limits the iteration to numbers less than 5 and increments by 1 each
time, then the result should be
- Change
the loop’s <continuation> test to be i<10.
Show the result. Change the
<next> field of the for-statement to increment by 2. Show the
result.
- Change
the for-statement to count down from 10 to 1 by 1. The <next>
calculation must subtract 1 on each cycle. Show the result.
- Save
the following GIF on your desktop and change it’s name to star.
- Revise
your iteration so that it just loops five times. (It doesn’t matter where
you start, stop or the amount you change the iteration variable by, as
long as the loop iterates only five times. Make the following statement be
the statement that is repeated:
document.write("<img
src='star.gif'>");
The result should look like the
following
- Think
about how this loop works and what it is placing in the HTML file of the
web page. What is happening? Ask your TA if you are not sure.
These exercises are useful for the last parts of Project 2.
Now use what you have learned to work on Project 2.