Cheat Sheet: Review of PHP Fundamentals

Variables

$string = "Tennessee";
$age = 24;
$double_age = 2 * $age;
$age_plus_ten = $age + 10;

Arrays

// numeric array (AKA indexed array)
	$items[0] = "orange";
	$items[1] = "apple";
	$items[2] = "pear";
	echo $items[1]; 		// outputs apple
	// associative array
	$items[username] = "Joe";
	$items[school] = "Watkins";

Conditions (Control Structures)

if ( $age > 20 ) { 
		echo "you are older than 20"; 
		echo " and that is great."; 
		}
	else {
			echo "you are younger than 20"; 
	}

Functions

// built-in to PHP
	$the_year_now = date('Y'); // stores 2012 in my variable
	// build your own
	function year_plus_one() {
		$output = 1 + date('Y');
		return $output; 
		}
	$the_year_plus_one = year_plus_one(); 
	$the_year_plus_two = $the_year_plus_one + 1;
	echo $the_year_plus_two; // outputs 2014

Loops

// FOR loop
		for ($i = 1; $i <=10; $i++) {	
			echo ("the counter is at $i");
			}
	// FOREACH loop (only for arrays)
		$items[username] = "Joe";
		$items[school] = "Watkins";
	foreach ($items as $key => $value) {
			echo ("For this element, the key is $key and the value is $value.");
		}

Exercise 8: Rock Paper Scissors

Write a program that lets a human user play Rock Paper Scissors against the computer. Playing the game should have the computer choose a random throw and then echo a string like this:

You threw Rock. Computer threw Paper. Computer wins.

In Terminal, type cd ~/Desktop and hit return. Now type ls and hit return. That should list all the files and folders on the Desktop, so you’re ready to run PHP files that are saved there. (You can review other Terminal commands on the Web 2 blog).

We want to run our script (say it’s called myscript.php) but also pass it a string that represents our “throw”. If you want to want play Scissors, type this:

php myscript.php "Scissors"

And here’s the beginning of the script we did in class:

<?php
// capture the user input (whatever they put after the filename in Terminal)
$user_throw = $argv[1];
// store possiblities in an array
$throws[0] = "Rock";
$throws[1] = "Paper";
$throws[2] = "Scissors";
$random_number = rand(0,2);
$computer_throw =  $throws[$random_number];
echo "\n\n\n\n";
echo "The user threw $user_throw";
echo "\n\n\n\n";
echo "And the Computer threw $computer_throw";
echo "\n\n\n\n";
?>

Bonus Round: Now convert your program into a function which picks a random throw for both User and Computer, plays them against each other, and keeps track of who won. It will look something like this:

function playgame($user_throw, $comp_throw) {
[code goes here]
}

Embed your function in a loop that runs the game 100 times. Output the winner of each game and also announce the total at the end (“User won 35, Computer won 35, and their were 30 ties”).

Update: Below are some possible solutions. There are probably many more ways to do this.

Exercise 8 Solution

Sun Spots Earth

Found this interesting horizontally scrolling website. It's supposed to be a very accurate representation of the size of planets to the sun and their distance. Based on the scale of the image of the sun.

www.phrenopolis.com

HTML5 Canvas

After a couple of tries I finally got the look I wanted. Give it a try yourself.

Starter Kit Structure

I should have posted something like this a few weeks ago, but anyway here’s a chart of the primary templates you’re using for your blog, and the way the includes get pulled in. Remember that there’s no requirement to use PHP includes in this particular way — the code in them could have been inserted directly into their parent templates. It’s just that since the code for “output a post” or “output a link to a post” is the kind of thing you tend to do on multiple templates, it makes sense to consolidate them into the files I’ve called “snippets.”

Finally, you’re of course free to tinker with any and all of the files; this just shows how Starter Kit was structured when you installed it:

Download Starter Kit