PHP Basics

General

• PHP stands for PHP: Hypertext Processor
• PHP is loosely typed
• PHP is case sensitive

Getting Started

• Comments
• echo "hi";

Scalar Types

• boolean: true, false
• float: 3.14, 1.2e4
• integer: 100
• string: "example 1", 'example 2'

Compound Types

• array (next lecture)
• object (in two lectures)

Variables and Constants

• $year = 2006;
• define("RATE", 1.27);

If Statement

• if (condition) {} else {}
• elseif

Switch Statement

switch ($variable)
{
  case 1:
    ...
    break;
  case 2:
    ...
    break;
  default:
    ...
}

Conditional Expressions

• equal: = =
• not equal: !=
• and: & &
• or: ||
• not: !

Loop Constructs

• while (condition) {}
• for ($i = 1; $i <= 10; $i++) {}
• do { } while (condition)
• break;
• continue;

User Defined Functions

function addOne ($number)
{
  return $number + 1;
}

// illustrates a function as a procedure
// uses a default value 
function bold ($string = "leipzig")
{
  echo "<b>" . $string . "</b>";
}

// pass by reference
function doubleValue (&$number)
{
  $number *= 2;
}

// static local variable
function count()
{
  static $count = 0;
  $count++;
  return count;
}

Defined Functions

• Here is an online reference

Function Reuse

• require "windows.inc";
• Note: you can modify the include_path variable of the php.ini file for functions that are reused in many different projects

Lecture Code

Write a php file that computes and prints all of the times between 0 hours and 12 hours (inclusive) when the hour hand and the minute hand of an analog clock are in alignment. The output of the php file should match this file exactly.

Solution

The clock.php file that we developed during class.

Laboratory

Do something interesting and non-trivial that uses some of today's material. If you are a Montana State student, demonstrate it during today's lab period. If you are a University of Leipzig student, either demonstrate it during today's lab period or e-mail it to Sebastian (loewe AT uni-leipzig.de) no later than the end of the day.