Web Design Wikiclass | Tutorial / Server-side Processing: Introduction to PHP Programming

Overview: This tutorial introduces PHP programming as the basic of server-side processing for Web development.

The Environment

To begin using PHP, you need to have a proper development and running environment set up.
PHP is usually used in combination with a Web server.
Requests for running PHP programs are received by the Web server, and are handled by the PHP interpreter.
The results obtained after execution are returned to the Web server, which takes care of transmitting them to the client browser.

Activity 1: Install XAMPP as a Web server in your PC

Go to apache friends - xampp for windows.
Install the XAMPP for Windows as instructed.
Start the Apache Web Server.
Go to the address http://localhost/ or http://127.0.0.1/ in your browser.
Note that all the web files are stored under the folder htdocs. We call it the document root of the Web server.

Activity 2: Test a simple PHP program running in your Web server

Creat a new folder under the document root of the Web server, say C:\xampp\htdocs\test-php\
In the new folder you just created, creat a new file with the following content, say say C:\xampp\htdocs\test-php\test.php

      <html>
      <head></head>
      <body>

      Agent: So who do you think you are, anyhow?
      <br />

      <?php
      // print output
      echo 'Neo: I am Neo, but my people call me The One.';
      ?>

      </body>
      </html>

Use your browser to access the PHP program.
Examine the HTML code received by the browser.

Q1) What your Web browser will receive from the server-side program?

Q2) Can we use a Web browser to get the source code of the server-side program?

PHP Syntax

PHP lets you embed PHP code in regular HTML pages, and execute the embedded PHP code when the page is requested.
These embedded PHP code is enclosed within special start and end tags:

      <?php

      ... PHP code ...

      ?>

For example,

      <html>
      <head>
      <title>My First PHP Page</title>
      </head>
      <body>
      <?php
        echo "Hello World! ";

        echo "Hello World! ";
        echo "Hello World! ";
        echo "Hello World! ";        echo "Hello World! ";
      ?>
      </body>
      </html>

The semicolon signifies the end of a PHP statement.
Whitespace is ignored between PHP statements.
PHP comments
- Single Line Comments, start with //
- Multiple Line Comments, start with /* and end with */
(They are similar to comments of other programming languages.)

PHP variables

A variable is a means of storing a value.
A variable is defined with the following form:

      $variable_name = Value;

Boolean variable specifies a true or false value.

      $found = true;

Integer variable

      $age = 34;

Floating-point variable specifies a fractional number

      $temperature = 21.89

String variable

      $car = 'BMW';

(Question: What is the major difference when it compares to other programming language you have learned?)

PHP operators

Assignment Operators

      $my_var = 4;
      $another_var = $my_var;

Arithmetic Operators

      + 	Addition
      - 	Subtraction
      * 	Multiplication
      / 	Division
      % 	Modulus

Relational operators / Comparison Operators

      == 	Equal To
      != 	Not Equal To
      < 	Less Than
      > 	Greater Than
      <= 	Less Than or Equal To
      >= 	Greater Than or Equal To

String Operators: the period "." is used to add two strings together

      $a = 'This is';
      $b = 'funny';
      $c = $a.' '.$b;

PHP's arrays

An array is a complex variable that allows you to store multiple values in a single variable
An array is handy when you need to store and represent related information.
Example 1:

      $pizzaToppings = array('onion', 'tomato', 'cheese', 'anchovies', 'ham');

Example 2:

      $fruits = array('red' => 'apple', 'yellow' => 'banana', 'purple' => 'plum');

Example 3:

      $pasta[0] = 'spaghetti';
      $pasta[1] = 'penne';
      $pasta[2] = 'macaroni';

Example 4:

      $menu['breakfast'] = 'bacon and eggs';
      $menu['lunch'] = 'roast beef';
      $menu['dinner'] = 'lasagna';

PHP's control statements

If Statement

      $name = "steven";
      if ( $name == "steven" ) {
        echo "Your name is Steven!<br />";
      }
      echo "Welcome to my homepage!";

If/Else statement

      if ( $number >= 3 ) {
        echo "The if statement evaluated to true";
      } else {
        echo "The if statement evaluated to false";
      }

For loop

      for ( initialize a counter; conditional statement; increment a counter){
        // do this code;
      }

      // Example
      for ( $counter = 10; $counter <= 100; $counter += 10) {
        // do something based on the counter;
      }

Foreach

      $pizzaToppings = array('onion', 'tomato', 'cheese', 'anchovies', 'ham');
      echo '<ol>';
      foreach ($pizzaToppings as $topping) {
          echo '<li>'.$topping.'</li>';
      }
      echo '</ol>';

Define and call functions

Create a function

      // define a function
      function getCircumference($radius) {
          $result = $radius*2*3.14;
          return $result;
      }

Call a function

      // call a function with an argument
      $the_radius = 10;
      $the_circumference = getCircumference($the_radius);

Activity 3: PHP For loop

Write a PHP program that outputs 12x12 times table like the following:

You can use HTML table to present the result:

    <table border="1" cellpadding="5">
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    <tr><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td><td>X</td></tr>
    </table>

Q3) Submit your PHP program for this activity.

Activity 4: PHP Control Statements

Write a PHP program that outputs the distribution of prime numbers in the following way:

Hint 1: The following PHP code is useful for you; it outputs all the prime numbers between 1 and 100.

      <?php
        for ($i = 1; $i <= 100; $i++)
        {
          if($i % 2 != 1) continue;
          $d = 3;
          $x = sqrt($i);
          while ($i % $d != 0 && $d < $x) $d += 2;
          if((($i % $d == 0 && $i != $d) * 1) == 0) echo $i.' ';
        }
      ?>

Hint 2: You can use the HTML tag <strong> and </strong> to bold a number.

Q4) Submit your PHP program for this activity.

References:

Submission

Please submit your work to Steven by email: sochoy@ouhk.edu.hk.
Please use SXXXXXXX - WD Tutorial 18 Submission as the email subject.