intro to php

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Intro To PHP

David Lash

Getting Started

With PHP

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Objectives To understand what PHP is

» What is HTML» How PHP compares with CGI

Getting Started with PHP» Your first script» PHP syntax and embedding in HTML» Finding out about your PHP configuration

Using PHP variables

» Numerical variables and operators

» String variables, operators and a few functions

Separating PHP from HTML using <?=

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Competencies

At end of unit be able to » Understand how PHP compares with other

dynamic technologies» Create a Web Page with PHP embedded» Receive input into PHP script with variables

Competency Alert:You need to

know this!

Common Problem Area!

People seem to forget this

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Ummm, What is HTML used for?

HTML primarily . . . » Provides instructions to browser on how file should display.

– Has a set of markup language commands

– Can include graphical image files

HTML documents are Static. » For example, cannot use HTML alone to:

– have a document display current time

– receive results of a form, query a database, and display the results

– Open an input file and based on its contents, display different document content

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Accessing HTML FilesYour PC

(Internet connected)Web Server

(Internet connected)

URL:www.myserver.com/funstuff.html

Web browser

Find Web server at www.myserver.comWeb server receives

request

Sends file withfunstuff.html

The file funstuff.htmlHere are some funthings to do:

1. Play baseball.2. Go swimming.3. Go to a concert.

Web browser

Note: The file is just

retrieved no code is executed on server

Note2: HTML tags

interpreted on client by browser.

http protocol

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HTML?

The Hypertext Markup Language (HTML)» used coded HTML tags » provide Web browsers display instructions.

HTML is» It is simple to use and understand» It provides ways to include things like text, graphics,

sounds, links.» It is STANDARD » Its creation (and use) is one of the big reasons the WWW

became popular

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Displaying HTML

DocumentTitle

Blue Text

Boldanditalic Text

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Major Server-Side Web Technologies

CGI - Computer Gateway Interface» Web Servers enable computer variety of computer

languages to dynamically generate HTML» E.g. Perl, C, Unix Shell, C++

Web Server add-on» Builds on to existing web servers – E.g., Cold Fusion

Embedded Web server» Web server has scripting language built into it.» Comprises most modern scripting technologies

– ASP, JSP, PHP

Competency Alert:You need to

know this!

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Often the Choice Depends on Web Server

If running a Microsoft Web Server (e.g., IIS) » More likely to use ASP or ASP.net

If running UNIX/Linux (e.g., Apache) » more likely to use PHP, or JSP.

Source netscrat http://www.netscraft.com

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What Is PHP?Advantages of Using PHP to enhance Web pages:

» Easy to use.» Open source.» Multiple platform.

Started around 1996 when » Rasmus Lerdorf (a consultant) wanted to know number of people viewing his on-

line resume. » Developed a CGI/Perl script that counted visitors and logged some visitor

information.» He received many inquires for his CGI/Perl toolset so started giving it away for

free (and called it Personal Home Page).» Got so many requests for additions, developed a next release of toolset (called

PHP 2.0)» PHP 2.0 became popular and PHP moved to open source model.

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How PHP Pages are Accessed and Interpreted

2. Send Request for PHP file

6. Return Results

Please EnterAPhoneNumber

Submit Erase

1. Web Browser

Web Browser

Phone QueryResults:

That isJohn Doe'sPhoneNumber

7. Web Browser

Your PC(Internet connected)

WebServer(Internet connected)

Web ServerSoftware

3. Receiverequest, find

file and read it.

4. ExecutePHP

statements

5. Sendresultsback.

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Objectives

To understand what PHP is » What is HTML» How PHP compares with CGI


Using PHP variables




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Getting Started with PHP

To develop and publish PHP scripts you need:

» A Web server with PHP built into it» A client machine with a basic text editor and

Internet connection» FTP or Telnet software

Its worth noting:There are a couple good IDEs for PHP. They basically allow you create PHP scripts on PC, syntax check them, see output, and then copy to Web server

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Common PHP Development Configurations

Linux/Apache

FTP or telnet

Development PC

Development PC

Windows/Apache/IIS

PC RunningWindows

Apache/IIS

PC RunningLinux Apache

Note, you can go to apache2triad.net and download php, mysql, apache onto your PC. It will install like any other PC program. It is big (70 MBs). It will allow you to run EVERYTHING WE DO without students.depaul.edu.

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Creating a PHP Script File and Saving It to a Local

Disk

You can use a number of different editors to create your PHP script files. » The PHP script starts with a <?php tag and ends with ?>. » Between these tags is a single PHP print statement.

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On a Linux/Apache Web Server

Typically you:

1. Save files with a .php suffix (myfile.php).

2. Place files under public_html (e.g., /home/dlash/public_html/

Save in public_html like any html file but use php suffix

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PHP Proper Syntax Need to be syntactically correct. For example, the print statement syntax:

print ( "Your message to print" );

Enclose messagein quotation

marks

Message to Output

End in asemi-colon

Parenthesis areoptional

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If Use Improper Syntax

Suppose you use the wrong syntax:

1. <?php2. print ( “A simple initial script);

3. ?>

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A Little About PHP's Syntax

Some PHP Syntax Issues: » Be careful to use quotation marks, parentheses, and

brackets in pairs.

» Most PHP commands end with a semicolon (;).

» Be careful of case.

» PHP ignores blank spaces.

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Embedding PHP Statements Within HTML

Documents1.<html>2.<head> 3.<title>HTML With PHP Embedded</title> </head>4.<body> 5.Welcome To My Page6.<?php7. print (" Using PHP is not hard ");8.?>9.and you can learn to use it quickly!

10. </body></html>

This statement runs first and THEN the output with other HTML is returned to browser

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Using Backslash (\) to Generate HTML Tags with

print() Sometimes you want to output an HTML tag

that also requires double quotation marks. » Use the backslash (“\”) character to signal that the

double quotation marks themselves should be

output:

print ("");» The above statement would output: 

Note! . . . You could also output the above line using the following PHP line:print (‘“’);We will examine the meaning between “ and ‘ later.

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Using Comments with PHP Scripts

Comment Syntax - Use //<?php// This is a comment?>

Can place on Same line as a statement:<?phpprint ("A simple initial script"); //Output a line?>

Note: Comment lines are ignored when the script runs. They do not slow down the run-time

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Alternative Comment Syntax

PHP allows a couple of additional ways to create comments.<?php

phpinfo(); # This is a built-in function

?>

Multiple line comments. <?php/*

A script that gets information about the

PHP version being used.

*/

<? phpinfo(); ?>

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More on phpinfo()

Use a script with the following to find out about your PHP installation:» <? phpinfo(); ?>

This build does NOT have mysql!

Location of PHP main config file

The php version

Other interesting items:Apache version & configuration, php config variables, environment.

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More on phpinfo()

Manual strongly recommends setting to off

Allow ASP style tages

Value constant

1 E_ERROR

2 E_WARNING

4 E_PARSE

8 E_NOTICE

16 E_CORE_ERROR

32 E_CORE_WARNING

64 E_COMPILE_ERROR

128 E_COMPILE_WARNING

256 E_USER_ERROR

512 E_USER_WARNING

1024 E_USER_NOTICE

2047 E_ALL

2048 E_STRICT

Flag values indicates which errors to display/log

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Error Definitions . . . Value Constant Description Note

1 E_ERROR (integer) Fatal run-time errors. These indicate errors that can not be recovered from, such as a

memory allocation problem. Execution of the script is halted.

2 E_WARNING (integer) Run-time warnings (non-fatal errors). Execution of the script is not halted.

4 E_PARSE (integer) Compile-time parse errors. Parse errors should only be generated by the parser.

8 E_NOTICE (integer) Run-time notices. Indicate that the script encountered something that could indicate an

error, but could also happen in the normal course of running a script.

16E_CORE_ERROR

(integer) Fatal errors that occur during PHP's initial startup. This is like an E_ERROR, except it is

generated by the core of PHP. since PHP 4

32E_CORE_WARNING

(integer) Warnings (non-fatal errors) that occur during PHP's initial startup. This is like an

E_WARNING, except it is generated by the core of PHP. since PHP 4

64E_COMPILE_ERROR

(integer) Fatal compile-time errors. This is like an E_ERROR, except it is generated by the Zend

Scripting Engine. since PHP 4

128E_COMPILE_WARNING

(integer) Compile-time warnings (non-fatal errors). This is like an E_WARNING, except it is

generated by the Zend Scripting Engine. since PHP 4

256E_USER_ERROR

(integer) User-generated error message. This is like an E_ERROR, except it is generated in PHP

code by using the PHP function trigger_error(). since PHP 4

512E_USER_WARNING

(integer) User-generated warning message. This is like an E_WARNING, except it is generated in

PHP code by using the PHP function trigger_error(). since PHP 4

1024E_USER_NOTICE

(integer) User-generated notice message. This is like an E_NOTICE, except it is generated in PHP

code by using the PHP function trigger_error(). since PHP 4

2047 E_ALL (integer) All errors and warnings, as supported, except of level E_STRICT.

2048 E_STRICT (integer) Run-time notices. Enable to have PHP suggest changes to your code which will ensure

the best interoperability and forward compatibility of your code. since PHP

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‘Overriding’ php.ini settings

<?php

ini_set('error_reporting', 2047);

phpinfo();

?>

Global is ’85’ Local is 2047.

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Apache2triad provide config administrator

Show errors in browser

Include HTML errors

Note: Has option at bottom to save configuration. Also must restart apache for changes to take effect.

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Setting Your own Configuration Options

<?php

ini_set('error_reporting', E_ALL);

$x = $y + 1;

print " x=$x $y=$y"

?>

2047 E_ALL (integer)

All errors and warnings, as supported, except of level E_STRICT.

2048 E_STRICT (integer)

Run-time notices. Enable to have PHP suggest changes to your code which will ensure the best interoperability and forward compatibility of your code.

since PHP

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Visit www.php.net

Quick function search

Function manual

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Objectives



Using PHP variables




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PHP allows creating variables on the fly

For example, <?php $days = 3; $newdays = 100; $days = $newdays;?>

A PHP variable names must:» Use a dollar sign ($) as the first character» Use a letter or an underscore character (_) as the

second character.

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Combining Variables and the print Statement

Use print statement with double quotes:

$age=6;

print ("Bryant is $age years old.");

print (‘but george is $age years old.’);

Would output: Bryant is 6 years old but george is $age years old.

Double quotes output any variable’s value

Single quotes output any variable’s name.

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Using Arithmetic Operators

PHP supports various arithmetic operators. For example

<?php

$apples = 12;

$oranges = 14;

$total_fruit = $apples + $oranges;

print ("The total number of fruit is $total_fruit");

?>

These PHP statements would output The total number of fruit is 26.

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Common PHP Numeric Operators

Table 2.1 Common PHP Numeric Operators

Operator Effect Example Result

+ Addition $x = 2 + 2; $x is assigned 4.

- Subtraction $y = 3; $y = $y – 1;

$y is assigned 2.

/ Division $y = 14 / 2;

$y is assigned 7.

* Multiplication $z = 4; $y = $z * 4;

$y is assigned 16.

% Remainde (modulus)

$y = 14 % 3; $y is assigned 2.

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Common PHP Combined Assignment Operators

Operator Effect Example Result

+= Addition and assignment

$y += 3; $y = $y + 3;

-= Subtraction and assignment

$y -= 3; $y = $y – 3;

*= Multiplcation and assignment

$y *= $x; $y = $y * $x ;

/= Division and assignment

$y /= 12; $y = $y / 12;

%= Modulus and assignment

$z %= $x; $z = $z % %x;

.= Catenation and assignment

$happy .= ‘hello’ ;

$happy = $happy . ‘hello’;

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A Full Example1. <html>

2. <head> <title>Variable Example </title> </head>

3. <body>

4. <?php

5. $columns = 20;

6. $rows = 12;

7. $total_seats = $rows * $columns;

8.

9. $ticket_cost = 3.75;

10. $total_revenue = $total_seats * $ticket_cost;

11.

12. $building_cost = 300;

13. $profit = $total_revenue - $building_cost;

14.

15. print ("Total Seats are $total_seats ");

16. print ("Total Revenue is $total_revenue ");

17. print ("Total Profit is $profit");

18. ?> </body> </html>

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WARNING: Using Variables with Undefined Values

Use a variable without a value assigned will have no value (called a null value).

PHP will NOT generate an error and will complete the expression.

For example,

<?php$y = 3;$y=$y + $x + 1; // $x has a null valueprint ("x=$x y=$y");?>

Will output x= y=4.

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PHP Precedence Rules PHP follows the precedence rules listed

below.» First it evaluates operators within parentheses.» Next it evaluates multiplication and division» Finally it evaluates addition and subtraction

For example, the first 2 statements evaluate to 80 while the last to 180.

$x = 100 - 10 * 2;$y = 100 - (10 * 2);$z = (100 - 10) * 2;

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Objectives



Using PHP variables




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Working with PHP String Variables

Use character strings for data such as customer names, addresses, product names, and descriptions.

E.g.,» $name="Christopher";» $preference="Milk Shake";

Note: Technically it is more correct to write: $name=‘Christopher’;$preference=‘Milk Shake’;Since there are no variable values to evaluate.

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WARNING: Be Careful Not to

Mix Variable Types Be careful not to mix string and numeric

variable types. <?php

$x ="banana";

$sum = 1 + $x;

print ("y=$sum");

?>

No error will occur instead will output:y=1

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Using the Concatenate Operator

The concatenate operator combines two separate string variables into one.

For example, » $fullname = $firstname . $lastname;

$fullname will receive the string values of $firstname and $lastname connected together.

For example, $firstname = "John";

$lastname = "Smith";

$fullname = $firstname . $lastname;

print ("Fullname=$fullname");

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TIP: Different ways to concatenate strings.

A couple different ways to concatenate strings:» Concatenation operator

$Fullname2 = $FirstName . " " . $LastName;

» Double quotes $Fullname2 = "$FirstName $LastName";

» Concatenation combination operator $comment = ‘I love this job’;

$comment .= ‘but the hours and not that good’;

» Mix and match: $name = ‘George’;

$comment = “$name said: I love this job”;

$comment .= ‘but the hours and not that good’;

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The strtolower() and strtoupper() Functions

These functions return the input string in all uppercase or all lowercase letters, respectively.

For example, <?php

$inquote = "Now Is The Time";

$lower = strtolower($inquote);

$upper = strtoupper($inquote);

print ("upper=$upper lower=$lower");

?>

Would output “upper=NOW IS THE TIME lower=now is the time”.

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Objectives



Using PHP variables




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Evaluation delimiters1 <?php23 $url = '<a href=http://mysite.com> mysite.com </a>';4 $store = ' toy store ';5 $special = 'boxed block sets';6 ?>7 <html>8 <head> <title> this is a title </title> </head>9 <body> 10 Welcome to the <?= $store ?>11 our special today is <?= $special ?> 12 Visit our home page at <?= $url ?>13 </body> </html>

Can separate PHP from HTML and use <?= delimiter. It automatically outputs any PHP variables found.

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Getting input data

To receive data with REGISTER_GOBALS OFF you use a special variable called $_GET.

» $mynm = $_GET[“name”];Enclose in squarebracket and then quotes

Name of HTML form CGI variable (note do not use $)

Special PHP Global variable. Technically it is an associative array (covered in chptr 5.)

PHP variable name that you want to receive the HTML form input.

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Sending Input From URL

You can send data to your application by: » http://www.indelible-learning.com/php/module1/input.php?special=Baseball Bats

If needed to send multiple input variables could:» http://www.indelible-learning.com/php/module1/input.php?special=Baseball Bats&myname=Dave

Use & sign

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Objectives



Using PHP variables




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Module 1 Hands on Assignment

Create a php script that calculates the total possible revenue of a theater. Suppose that:» The theater charges $5 per seat» The theater has with 10 rows and 8 seats per row. » Output the total possible revenue.» Set the seat cost, rows and seats per row at top of script

and separate PHP from HTML code.

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One possible solution

1 <?php 2 $cost = 5; $rows = 10; 3 $cols = 8; $total = $rows * $cols; 4 $rev = $cost * $total; 5 ?> 6 <html> 7 <head> <title> Theater Calculation </title> </head> 8 <body> 9 We have <?= $total ?> seats in the house 10 11 At a costs of $<?=$cost ?> our total possible revenue is 12 <?= $rev ?>. 13 </body> </html>

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Lab 1 Extension Exercise

Modify that same script to receive the values of $rows and $cols from the Web URL. » Send different input values from the web

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One Possible Solution <?php $cost = 5; $rows = $_GET[rows]; $cols = $_GET[cols]; $total = $rows * $cols; $rev = $cost * $total; ?> <html> <head> <title> Theater Calculation </title> </head> <body> We have <?= $total ?> seats in the house At a costs of $<?=$cost ?> our total possible revenue is <?= $rev ?>. </body> </html>