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Introduction to PHP development
Introduction to PHP development
Daniel ReevesWeb Applications Developer
ResNET UNC Chapel Hill
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My AssumptionsMy Assumptions
Introductory class Skill Level Programming concepts Topics Covered Future Presentations Mind Numbing Materials
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OutlineOutline
Introduction PHP Basics Programming and PHP PHP Topics Questions
IntroductionIntroduction
Questions for youQuestions for you
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MaterialsMaterials
Location• http://webmasters.unc.edu/presentation
s/
• ZIP file of all materials (ppt, handout, code)
Handout• Terms, tips, Google search strategies
PowerPoint Video
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To PHP or not to PHP? The Pros
To PHP or not to PHP? The Pros
Great Documentation Allows coding to modern standards Open Source Global and Diverse Developer
Community Don’t have to reinvent the wheel Total Programmer Control Easy to deploy
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To PHP or not to PHP? The Cons
To PHP or not to PHP? The Cons
Inconsistent function names Only Basic scoping Constantly Evolving Total Programmer Control Not most efficient language
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Google it !!!!!Google it !!!!!
When in doubt, search! Search before you build Properly formed Searches on Google
• Google’s autocomplete is
For PHP searches, start by typing “php”• Suggestions will start to show
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Programming Philosophy
Programming Philosophy
Architecture Analogy• Structure: Problem/Constraints/Solution• Materials• Tools (data structures)
4 general uses: • automation, iteration/reuse, functionality,
uniformity
Know Thy Enemy Pure problem solving
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Programming TipsProgramming Tips
Process Sequentially Save often, keep multiple versions Test incrementally Reuse code, copy and paste Start small and build Solving problems is a mental process Walk away and come back
PHP BasicsPHP Basics
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Client/ServerClient/Server
Client = User’s Browser Server = Websites, Online files PHP server only Can only process when …
• When a page is requested• After a user action has submitted the
page
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What can one do with PHP?
What can one do with PHP?
Database Programming
File Read/Write Form Processing Form Validation Ajax Interaction PDF Creation File Search and
Archive
Interact with web APIs
Interact with MS Office
Image Processing and
Chart Creation XML file Read/Write Sending Email Writing Code
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Topics for TodayTopics for Today
Basic PHP/HTML interaction• Creating HTML with PHP
PHP form validation and processing• Server request interaction• Input validation
Basic debugging and error trapping• Methods for finding and correcting errors
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What you needWhat you need
Server space where PHP is enabled• http://help.unc.edu/108
Editing program to write the code in• Notepad++ good, free editor for coding
HTML Browser for viewing created pages• Firefox is my preference
Second monitor – recommended
Programming PHPProgramming PHP
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Writing Clean CodeWriting Clean Code
Writing Clean Code• Using tabs for code, white space, line
breaks• Ex: which looks cleaner, easier to read?
<?php echo “test”; $foo++; ?>
OR
<?php
echo “test”;
$foo++;
?>
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PHP file, <?php tag, & ‘;’
PHP file, <?php tag, & ‘;’
Files end in .php (ex: contact_form.php)
Server recognizes code within <?php tag
Requires ?> closing tag When writing opening tag, write
closing Code not in PHP tags displays as
HTML End statements with ;
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Example – php_tagsExample – php_tags
<?php
?>
testing
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Errors and Error Messages
Errors and Error Messages
Empty Page• Difficult, frustrating when page is just
blank
Turn on Errors• On Handout: ini_set('display_errors',1);
Shows warnings and errors Dangerous for production code
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Example – php_errorsExample – php_errors
<?php
ini_set('display_errors',1);
?>
testing
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PHP Programming – Hello World
PHP Programming – Hello World
How do I know if PHP is turned on?• php_info();
“Hello World” Echo statement Single/Double quotes in PHP
• echo “testing”; same as echo ‘testing’;• Use double quotes for variables
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Example – Hello World
Example – Hello World
<?php
ini_set('display_errors',1);
php_info();
echo “Hello World”;
?>
testing
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What are Variables ?What are Variables ?
Basic building block of programming Stores information/data 3 basic parts: name, type and value Variables store different types of data
• Numbers, Strings, Boolean (True/False)
PHP Initialization PHP Types
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PHP Variable SyntaxPHP Variable Syntax
All variables start with “$” Any combination of letters, numbers,
“_” Variable Type Examples
• Ex: $customer = “Daniel Reeves”;• Ex: $cost = 1.25;• Ex: $is_administrator = true;
Will use $foo as default variable• $foo, $foo1, $foo2, etc.
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Manipulating Variables
Manipulating Variables
Set Variables • $foo = 1; $foo = “test”; $foo1 =
$foo
Display Variables• echo $foo; echo “$foo”;
Change and Combine text• $foo = “testing”.“ is fun”;• $foo1 = “Foo’s Value is: $foo”;
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And Arrays?And Arrays?
Collections of variable values Access various elements from index Index number or keyword
• 1st element starts at 0
Format: $array_name[‘index’] Array elements same as variables Mostly for form processing
• $_GET, $_POST
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PHP Array SyntaxPHP Array Syntax
Create• $numbers = array(1,2,3,4,5);• $names = array(‘fn’=>”Bob”,
‘ln’=>”Smith”);
Numbers 5 = $numbers[4];
Strings• “Bob” = $names[‘fn’];• “Bob” = $names[0];
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Conditionals – If/Then/Else
Conditionals – If/Then/Else
Need to test truth values If/ Else If/Else Establish consequences based on
test Allows for options Example: Contact form
• Category for student major• When submitted, choice would be tested• Assign a different action per major
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Conditionals – PHP Syntax
Conditionals – PHP Syntax
Syntax: if( testcondition ){ code } Syntax for if, else:
• if( testcondition ){ code }• else if( testcondition ){ code }• else {code}
Test values with: <, <=, >, >=, !, ==, !=
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PHP Programming – Functions
PHP Programming – Functions
Reuse Separate code Elements
• Name, Parameters, Code, Return
Many system functions available• include(); php_info(); echo “”;
Ex: function strlen($foo);• Returns number of characters in string
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Review – PHP BasicsReview – PHP Basics
<?php and ?> tags, required “;” Turn on errors and error messages Variables
• Strings, Numbers, Boolean (T/F)
Arrays Conditionals Functions
PHP topics – basic PHP and HTML
PHP topics – basic PHP and HTML
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Adding Dynamic Content
Adding Dynamic Content
Use variables 2 Philosophies 2 ways to display information Echo
• echo “First Name: $first_name”;
In HTML• First Name: <?= $first_name ?>
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Example – hello_world2
Example – hello_world2
<?php
$first_name = “Bob”;
$last_name = “Smith”;
echo “<html><body>”;
?>
<p>
My Name is: <?= $first_name ?> <?= $last_name?>
</p>
</body></html>
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Creating HTML with PHP
Creating HTML with PHP
HTML Break and new line• To write new line to document, use \n• To add new line to rendered HTML, use
<br>
Build then display HTML put just below php on page
• Nice segregation of server, client sides• Much easier to comment and debug
Create JS with PHP too
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Display HTML uniformity
Display HTML uniformity
Includes• Headers, footers, menus
Widths, heights• Easily keep for element sizes uniform
Naming conventions• Prefix for names or css classes
Other repeated code• Especially if it may ever change
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Review – PHP and HTML
Review – PHP and HTML
Adding dynamic content Use Variables Output to screen: echo, <?= ?> Breaks <br> and New Lines \n Display Uniformity
• Includes, reuse, naming, cohesive form items
PHP topics – PHP form processing and validation
PHP topics – PHP form processing and validation
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PHP and form submission
PHP and form submission
Process of filling out a form Where PHP gets access to form GET and POST PHP and request information
• GET and POST arrays• $_GET[‘form element name’];• $_POST[‘form element name’];
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Getting data from your request
Getting data from your request
Good first test: use GET• Can see parameters you are sending• Don’t need form• Print entire $_GET array: print_r($_GET);
Set items from GET to variables• Use same name as name you sent
Once variable, can process further
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Example - getExample - get
<?php
print_r($_GET);
if($_GET){
$foo = $_GET['passed_value'];
} else { $foo = "Empty"; }
?>
Value is: <?= $foo ?>
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EXAMPLE – contact_form
EXAMPLE – contact_form
<html><body>
<form action=“contact_form.php” method=“get”>
Input: <input type=“text” name=“passed_value” value=“<?= $foo ?>”>
<input type=“submit” value=“Submit”>
</form>
</body></html>
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Validation OptionsValidation Options
Cleaning user input discussed later Multiple validations of data Client = JavaScript, Server = PHP
• JS can be turned off from client, PHP cannot
• Test both ends, safer, better use experience
Validation proportional to importance Separate from security
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Using PHP for validation
Using PHP for validation
Test multiple issues for same value Test with conditionals Test for empty values
• If($foo == “”) { do something }
Flags = Boolean variables (T/F) Use variable to verify validation
• Set to true• If any validation fails, set it to false
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EXAMPLE – contact_form (above
form)
EXAMPLE – contact_form (above
form)<?php
if($_GET){
$foo = $_GET[‘passed_value’];
$form_passes = true;
if($foo == “”){ $form_passes = false; }
if(strlen($foo) < 5) {$form_passes = false; }
if($form_passes){ finish processing }
}
?>
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Redisplay and Error notification
Redisplay and Error notification
Good idea to redisplay form• Can redisplay all submitted information
Easy to find & read error messages• DIV at top of page, red and bold text• Tailored message for each issue
Interact with JS if helpful PHP mark the fields in error
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Process for ValidationProcess for Validation
User Submits page to server Use PHP to get information Test information
• Not empty, length
Errors and Redisplay• Show messages• Mark errors
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Review – PHP and Forms
Review – PHP and Forms
PHP gets form data at submission $_GET, $_POST and variables Validation
• Conditionals• Functions
Error notification and Redisplay• Communicate clearly with user
PHP topics – Debugging Errors
PHP topics – Debugging Errors
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The fun of errorsThe fun of errors
Programming requires proper syntax One error, entire page wont run Bad code can crash servers (unlikely) Example: Mariner 1 Rocket Realistic Worries
• Angering ITS Gods (Gogan does not approve)
• Loss, Compromise of data
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Common mistakesCommon mistakes
Misspelling variable names Leaving semicolon off Not closing PHP tag Quotes within quotes Refresh page Not saving work
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Commenting CodeCommenting Code
Comments• PHP does not run in comments
2 Uses• Removing code from page• Document what the code does
2 ways: // or /* … */• Single vs. Multi-line comments
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Example - commentsExample - comments
<?php
ini_set('display_errors',1);
/* Broken Code */
echo “broke“
//Working Code
echo “works";
?>
testing
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Example – commentsExample – comments
<?php
ini_set('display_errors',1);
/* Broken Code
echo “broke“ */
//Working Code
echo “works";
?>
testing
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die(); to the rescuedie(); to the rescue
PHP system function Will stop any PHP immediately Process to find errors
• Start with error message, may be simple• Put a die statement at top of page• Move down page section by section• When die no longer works, have found
error• Error is in the last block of code you past
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Example – die();Example – die();
<?php
die(‘testing1’);
ini_set('display_errors',1);
echo "works";
echo "broke"
?>
testing
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Example – die();Example – die();
<?php
ini_set('display_errors',1);
die(‘testing1’);
echo “works";
echo “broke“
?>
testing
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Example – die();Example – die();
<?php
ini_set('display_errors',1);
echo “works";
die(‘testing1’);
echo “broke“
?>
testing
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Example – die();Example – die();
<?php
ini_set('display_errors',1);
echo “works";
echo “broke“
die(‘testing1’);
?>
testing
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Review – Debugging PHP
Review – Debugging PHP
Errors are fun Common Mistakes Comment Code Die function Process for finding errors
Final words on PHPFinal words on PHP
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My takeMy take
PHP highly powerful, useful web tool• Can do everything I need efficiently• Unique properties great bonus• PHP my favorite by far
Use what you like• Make sure its open source if you can• Coding should be challenging but fun
Big picture, how programming can help
Questions?Questions?
