CS1109 Lab 14

Put the work for this lab into a new folder public_html\cs1109\lab14.

The first four parts of the lab sheet do not require much thinking, and should take less than 45 minutes.

Part 1: for practice

In a file called for.php, write a PHP script that uses for-loops to output each of the following:

Ten numbers: 0 1 2 3 4 5 6 7 8 9

Eleven numbers: 0 1 2 3 4 5 6 7 8 9 10

Teenage years: 13 14 15 16 17 18 19

Evens: 2 4 6 8 10 12 14 16 18 20

Descending odds: 19 17 15 13 11 9 7 5 3 1

Part 2: Slip into something more comfortable?

This exercise is also for practice: to see if you know how to invoke my validation functions correctly.

Take a copy of dress.html; do not edit it. It allows the user to enter his/her dress size.

Write dress.php, which validates the user's dress size. It must be an integer between 4 and 24 inclusive. If it isn't, then output the error message(s) from my validation function. If the size is OK, then echo it.

Ask one of us to check your PHP before you move on to the next exercise.

Part 3: Get the picture?

So far, our PHP scripts use echo commands to output HTML. Each script produces a web page that gets sent back to the client, e.g. to the user's browser, for display.

But there's nothing to stop us from writing PHP scripts that output things other than web pages. For example, we could write a PHP script that outputs a CSS stylesheet, if we want.

More fun, perhaps, we can output images. Building on what you already learned in CS1107, we will use PHP to output PNG images.

Create a file called rectangle.php and enter exactly and only what you see below but without the line numbers:

01 <?php
02     $width = 200;
03     $height = 300;
04     $im = imagecreatetruecolor($width, $height);
06     $yellow = imagecolorallocate($im, 255, 255, 0);
07     $blue = imagecolorallocate($im, 0, 0, 255);
09     imagefill($im, 0, 0, $yellow);
11     imagerectangle($im, 20, 10, 180, 290, $blue);
13     header('Content-type: image/png');
14     imagepng($im);
15     imagedestroy($im);
16 ?>

Note that you do not include any HTML. This is because the output is a PNG, not a Web page. Feel free to ask if you need more explanation.

Briefly, here is what is going on.

Once you've entered the above into your file, run the script in the usual way, and a PNG image should appear: a blue rectangle on a yellow background, like this:

A blue rectangle on a yellow background

Part 4: Now it's your turn

Take a copy of circle.html; do not edit it. It allows the user to enter the diameter of a circle.

You must write circle.php, which outputs a 200 by 200 pixel PNG containing a circle that has the specified diameter. The border of the circle should be red on a yellow background. The user's input must be checked ('validated') to ensure that it is an integer between 10 and 100 inclusive. Place an error message into the PNG if the user's input is invalid.

For example, if the user enters a diameter of 50, your script will produce a PNG like this:

A red circle on a yellow background

But if the user enters 101, s/he will see a PNG like this:

A failed red circle on a yellow background

Some notes:

Part 5: Flags of the world

Take a copy of flag.html; do not modify it:

You must write flag.php, which draws a flag and outputs it as a PNG. Here are some details:

Part 6: Lines under my eyes

Take a copy of line.html; do not edit it. It allows the user to enter two integers, referred to as m (an integer between 10 and 30 inc.) and n (an even integer between 2 and 20 inc.).

You must write line.php. If the user's input validates, then it outputs a PNG whose width and height are both m × n + 1. The image contains n pairs of red lines. Each pair contains either a horizontal or vertical line of length m and then a diagonal. Hard to explain, but easy to see by running mine:

Some notes:

Deadline for Lab 14: 1pm, Tuesday 12th February.

If you have named your files and folders correctly, your work will be collected automatically at that time by my software.

Challenge exercise

Remember that challenge exercises are always optional. They do not form part of your year's work and they are not worth any marks. They are designed for those students who finish the main exercise quickly and easily, and wish to explore further.

Take a copy of darts.html; do not edit it. It allows the user to enter how wide (and high) she wishes her image to be.

You must write darts.php, which draws a darts board and outputs it as a PNG of the specified size.

Leave both files in your lab14 folder, and I will take a look at them.