Introduction to PHP (Hypertxet PreProcessor, HyperText Processor)

Part 1 of 2

References

· Chapter 8 Introduction to Server-Side Development with PHP of the Text Book Entitled Fundamentals of Web Development, by Randy Connolly and Ricardo Hoar

· PHP 5.6.26, Sept. 16, 2016; PHP 5.6.14 Released Oct. 1, 2015; PHP 5.6.1 Released Oct. 2, 2014, http://php.net/

· PPH Documentation, http://php.net/urlhowto.php

· PHP Language Reference, http://php.net/manual/en/langref.php

o Basic Syntax

o Data Types

o Variables

o Constants

o Expressions

o Operators

o Control Structure

o Include Files

o Classes and Objects

o Namespaces

o Exceptions

o Predefined Variables

Basic Syntax

PHP Tags

<? …. ?> shorthand version of <?php ….?>

….

</script>

PHP Comments: three types of Comments

/* */ Multiple-line comment, Block comment

// End-of-line comment, One line comment at the end of the statement

# Single-line comment, at the beginning of the line

PHP Data Types

· Boolean // true, false

· Integer // whole numbers

· Float // Decimal numbers

· String // Letters, characters

· Array // A collection of data of various data types

· Object // Instances of classes

Variables

· Case sensitive

· Loosely types

· Always start with the $ symbol before the variable name

· Examples

o $count = 42;

o $id = 1234;

o $artist1 =”Picasso”;

o $artist2 =”Raphael”;

o $php5 = ‘version’;

o $os = “Microsoft Windows Prof 7”;

o $this_int = 50; // Standard decimal notation

o $that_int = 062; // Octal number

o $my_int = 0x32; //Hexadecimal

Variable Manipulation
<?php

$sum = 10 + 2; //12

echo($sum);

$sum = $sum + 5; //17

echo “$sum = ” . $sum;

$sum = %sum % 2; //1

$answer = 5;

$answer += 2;

$answer *= 2;

$answer ++;

$answer --;

String Escape Sequences (Escape Characters) in PHP

Escape String	Meaning
\n	New line
\t	Horizontal tab
\\	Back slash character
\$	$ character
\’	Single quote
\”	Double quote
\###	ASCII character (octal)
\x##	ASCII character (hexadecimal)

Constants

· Typically defined near the top of PHP file via the define() function

· Examples

<?php

# uppercase for constants – programming convention

define(“DATABASE_LOCAL”, “localhost”);

define(“DATABASE_NAME”, “ArtStore”);

define(“DATABASE_USER”, “Fred”);

define(“DATABASE_PASSWD”, “F5^7%ad”);

….

…

$db = new mysqli(DATABASE_LOCAL, DATABASE_NAME, DATABASE_USER, DATABASE_NAME);

Control Structures

· if .. else

· switch .. case

· while, do while

· for

Include Files

· include “somefile.php”

· include_once “somefile.php”

· require “somefile.php”

· require_once “somefile.php”

Reference to Include File PHP Scripts Examples

include “files.php”; // http://php.net/manual/en/function.include.php

include_once “file.php”; // http://php.net/manual/en/function.include-once.php

require (‘library.inc’); // http://php.net/manual/en/function.require.php

Functions

· PHP Built-in

o echo() //Output to HTML

o define() // Define constants

o printf() // Formatted output

· User Defined

o Syntax: function, return

o Calling a function

o Parameters

§ Passing by values

§ Passing by reference

o Variable scopes

Example:

* This function returns nicely formatted System Time string using the current

* System time.

function getTime(){

return date(“H:1:s”);

}

/* This function outputs the footer menu

function outputFooterMenu() {

echo ‘<dic id=”footer”>’;

echo ‘<a href=#>Home </a> | <a href=#Product</a> | ’;

echo ‘<a href=#>About us </a> | <a href=#Contact us</a>’;

echo ‘<div>’;

}

Example: variable-manip.hph, http://www.etcs.ipfw.edu/~lin/CPET499-ITC250/Lin-php-examples/variable-manip.php

<? php

$answer = 10;

echo(++$answer).” “;

echo “$answer<BR>”;

$answer += 10;

echo ($answer++).” “;

echo $answer; ?

unset($answer); //destroy the variable

<?php

%thankyou_string = “Thank you “;

%thankyou_string = thankyou_string . “for your comments!”;

// String concatenation operator period .

Predefined Variables

· $Superglobals // Bulit-in variables that are always available in all scopes

· $GLOBALS // All variables available in global scope

· $_SERVER // Server and execution environment info

· $_GET // HTTP GET variables

· $_POST // HTTP POST variables

· $_FILES // HTTP file upload variables

· $_REQUEST // HTTP request variables

· $_SESSION // Session variables

· $_ENV // Environment variables

· $_COOKIE // HTTP cookies

· $php_errormsg

· $HTTP_RAW_POST_DATA // Raw POST data

· $http_response_header // HTTP response headers

· $argc // The number of arguments passed to script

· $argv // Array arguments passed to script

PHP Functions Reference

· echo()

· unset() // Destroy variables

· func_get_args() // get function arguments

· func_num_args() // get function argument count

String Manipulation Functions

· strcmp() // string comparison, case sensitive

· strcasecmp() // string comparison, non case sensitive

· substr() // the sub string

· strlen() // The number of chars in the string

· strops() // The character position

· chop() // Remove all white spaces from its ends

· trim() // remove all white spaces from both ends

· strtolower() // covert to lower case characters

· strtoupper() // convert to upper case characters

Arithmetic Functions

· floor(), ceil(), round(), srand(), rand(), abs(), min(), max()

Ouput Functions

· print()

· printf() // formatted output

PHP Functions

· func_get_args() // http://us3.php.net/manual/en/function.func-get-args.php

· func_num_args()

Example: funct_arguments.php, http://www.etcs.ipfw.edu/~lin/CPET499-ITC250/Lin-php-examples/funct_arguments.php

<!DOCTYPE html>

<!—funct_arguments.php - A trivial example to illustrate a php document -->

<head>

<title> funct_arguments.php </title>

</head>

<body>

<?php

function func_dynamic() {

echo “ITC 250/CPET 499 Web Systems: “.func_num_args(). “Number of arguments.<br>”;

$args = func_get_args();

for($i = 0; $i < count($args); $i++{

echo “Passed arguments: {args[$i]} <br>;

}

func_dynamic(5, 4, 3, 2, 1 );

</body>

</html>