Open Source Server Side Scripting ECA 236 Open Source Server Side Scripting PHP Basics

Open Source Server Side Scripting 2 ECA 236 PHP Browser Server PHP.php Request Response Three types of errors can occur: 1.Parse 2.Execution 3.Logic

Open Source Server Side Scripting 3 ECA 236  4 different styles of PHP tags:  XML style  Short style  Script style  ASP style Basic Syntax

Open Source Server Side Scripting 4 ECA 236 Basic Syntax cont …  Files end with the extension.php  All statements end with a semicolon  White space is ignored  3 styles of comments: # comments // comments /* comments */

Open Source Server Side Scripting 5 ECA 236 Basic Syntax cont …  All class assignments must contain, in comments: Name Date Name of Assignment Purpose of Assignment /*Michael Barath 3 September 2003 Lab #3 Use loops and conditional to create and format a table */

Open Source Server Side Scripting 6 ECA 236 Variables  Naming Rules:  prefixed with a $  begin with letter or underscore  may contain only letters, number, underscores  case sensitive  Assign a value with the assignment operator ( = )  Do not have to be declared before use $first_name = “Michael”;

Open Source Server Side Scripting 7 ECA 236 Variables cont …  Variable Types  strings  integers  floating-point  Boolean  array  object  resources – special variable, holding a reference to an external resource such as an open file, database connection, or image canvas  NULL – a variable that has no value

Open Source Server Side Scripting 8 ECA 236 Sending data to browser  Built-in functions to send data to browser:  echo( ) allows you to send one or multiple pieces of code, separated by commas $first_name = “Michael”; $greeting = “How are you?”; echo “Hello, $first_name. $greeting”; echo “Hello, ”, $first_name, “.”, $greeting;

Open Source Server Side Scripting 9 ECA 236 Sending data to browser cont …  Built-in functions to send data to browser:  print( ) returns a value of TRUE or FALSE, if the function was called successfully  Technically neither echo( ) nor print( ) is a true function, but a language construct $first_name = “Michael”; $greeting = “How are you?”; print “Hello, $first_name. $greeting”;

Open Source Server Side Scripting 10 ECA 236 Strings  Blocks of textual information  Double Quotes  interpolated variables $name = “Michael”; echo “My name is $name”; // prints “My name is Michael”

Open Source Server Side Scripting 11 ECA 236 Strings cont …  Single Quotes  literals $name = “Michael”; echo ‘My name is $name’; // prints “My name is $name”

Open Source Server Side Scripting 12 ECA 236 Strings cont …  Use \ to escape quotes, $, \, etc $name = “Michael”; echo “$name said, \”Bob owes me \$20.\” ”; // prints Michael said, “Bob owes me $20.” echo ‘Michael\’s reply was “What, me worry?” ’; // prints Michael’s reply was “What, me worry?”

Open Source Server Side Scripting 13 ECA 236 Strings cont …  Concatenation Operator  dot, or period $first_name = “Jacques”; $last_name = “Renault”; echo $whole_name = $first_name. $last_name; // prints JacquesRenault echo $whole_name = $first_name. “ “. $last_name; // prints Jacques Renault

Open Source Server Side Scripting 14 ECA 236 Strings cont …  newlines and tabs \n \t  adds returns or tabs to the way code prints, not the way a document renders in the browser echo “ My Title ”; // prints My Title

Open Source Server Side Scripting 15 ECA 236 Strings cont …  newlines and tabs cont … echo “ \n \n\t My Title \n ”; /* prints My Title */

Open Source Server Side Scripting 16 ECA 236 Strings cont …  newlines and tabs cont … echo “ ”; echo “\t My Title ”; echo “ ”; /* prints My Title */

Open Source Server Side Scripting 17 ECA 236 Numbers  integer and floating point  Standard arithmetic operators: +addition –subtraction *multiplication /division $x = 7; $y = 3; $z = $x * $y ; // 21

Open Source Server Side Scripting 18 ECA 236 Numbers cont …  Standard arithmetic operators: %modulus  remainder, after division has occurred $x = 7; $y = 3; $z = $x % $y ; // 1

Open Source Server Side Scripting 19 ECA 236 Numbers cont …  Standard arithmetic operators: + +increment – –decrement $x = 7; echo $x++ ; // prints 7 echo ++$x ; // prints 8 $x = 7; echo $x- - ; // prints 7 echo - - $x ; // prints 6

Open Source Server Side Scripting 20 ECA 236 Numbers cont …  PHP includes dozens of functions to use with numbers. EG:  round( ) – rounds a decimal to the nearest integer takes one or two arguments  number to be rounded  number of decimal places $x = ; $x = round( $ ); // 313 $x = round( $x, 3 ); // $x = round( $x, - 2 ); // 300

Open Source Server Side Scripting 21 ECA 236 Numbers cont …  PHP includes dozens of functions to use with numbers. EG:  number_format( ) – groups number into thousands, comma takes one or two arguments  number to be formatted  number of decimal places $x = ; $x = number_format( $x ); // 43,905 $x = number_format( $x, 2 ); // 43,905.31

Open Source Server Side Scripting 22 ECA 236 Variables and CONSTANTS  CONSTANTS  Unlike variables, retain initial value throughout script  Use define( ) to create  Constants are usually named with all CAPS  No $ prefixes a CONSTANT  Cannot use echo( ) as you would with variables define( ‘NAME’, ‘Michael’ ); echo “Hello, “, NAME ; echo “Hello, “. NAME ;

Open Source Server Side Scripting 23 ECA 236 PHP’s Predefined Variables Superglobals  $_SERVER  $_GET  $_POST  $_COOKIE  $_FILES  $_ENV  $_REQUEST  $_SESSION

Open Source Server Side Scripting 24 ECA 236 Variable Scope  Superglobal variables are visible everywhere  Global variables within a script are visible throughout the script, but not inside functions  Variable used inside functions are local to the function  Variables used inside a function that are declared as global, refer to the global variables of the same name