Introduction to php
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Introduction to PHP. MIS 3501, Fall 2014 Jeremy Shafer Department of MIS Fox School of Business Temple University September 2, 2014. An Illustration – HTML only. URL, referencing a .html page. HTTP Response. An Illustration (developer, working remotely).

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Introduction to php

Introduction to PHP

MIS 3501, Fall 2014

Jeremy Shafer

Department of MIS

Fox School of Business

Temple University

September 2, 2014


An illustration html only

An Illustration – HTML only

URL, referencing a .html page

HTTP Response


An illustration developer working remotely

An Illustration (developer, working remotely)

Upload his / her work via sftp (port 22)

XAMPP installed locally. Use it to store and test your work until it is ready to be sent to the server.


An illustration php

An Illustration – PHP

PHP Interpreter

URL, referencing a .php page

HTTP Response

Database


Creating basic php scripts

Creating Basic PHP Scripts

  • Embedded language refers to code that is embedded within a Web page (HTML document)

  • PHP code is typed directly into a Web page as a separate section

  • A Web page containing PHP code must be saved with an extension of .php to be processed by the scripting engine

  • PHP code is never sent to a client's Web browser; only the output of the processing is sent to the browser


Creating basic php scripts continued

Creating Basic PHP Scripts (continued)

  • The Web page generated from the PHP code, and HTML elements found within the PHP file, is returned to the client

  • A web page that does not contain any PHP code should be saved with an .html extension

  • .phpis the default extension that most Web servers use to process PHP scripts


Creating php code blocks

Creating PHP Code Blocks

  • Code declaration blocks are separate sections on a Web page that are interpreted by the scripting engine

  • There are four types of code declaration blocks.

  • The one we care about:

    • Standard PHP script delimiters <?php … ?>

  • The rest:

    • The <script> element

    • Short PHP script delimiters <? ?>

    • ASP-style script delimiters <% %>


Standard php script delimiters

Standard PHP Script Delimiters

  • A delimiter is a character or sequence of characters used to mark the beginning and end of a code segment

  • The standard method of writing PHP code declaration blocks is to use the <?php and ?> script delimiters

  • The individual lines of code that make up a PHP script are called statements

  • PHP statements typically end with a semicolon ;


Displaying script results

Displaying Script Results

  • The echo and print commands are language constructs (built-in features of a programming language) that create new text on a Web page that is returned as a response to a client

  • The text passed to the echo statement must be enclosed in either single or double quotation marks


Displaying script results continued

Displaying Script Results (continued)

PHP Programming with MySQL, 2nd Edition

  • Use echo and print statements to return the results of a PHP script within a Web page that is returned to a client

  • For the sake of consistency, we will use echofrom here on out.


Let s give it a try

Let's give it a try…

  • Start Apache locally

  • Put template.html in the htdocs folder

  • Create a helloworld.html file. Test it.

  • Now rename itto create helloworld.php

  • Add some embedded PHP code in the <body> like this:

    <?php

    echo("Hello World!");

    ?>

  • Can you pull the page up in your browser?

  • Experiment by moving the block of PHP code.

  • Experiment by changing the appearance of the "Hello World" text using HTML tags


Creating multiple code declaration blocks

Creating Multiple Code Declaration Blocks

  • For multiple script sections in a document, include a separate code declaration block for each section

    ...

    </head>

    <body>

    <h1>Multiple Script Sections</h1>

    <h2>First Script Section</h2>

    <?php echo("<p>Output from the first script section.</p>");

    ?>

    <h2>Second Script Section</h2>

    <?php echo("<p>Output from the second scriptsection.</p>");?>

    </body>

    </html>


Creating multiple code declaration blocks continued

Creating Multiple Code Declaration Blocks (continued)

  • PHP code declaration blocks execute on a Web server before a Web page is sent to a client

    ...

    </head>

    <body>

    <h1>Multiple Script Sections</h1>

    <h2>First Script Section</h2>

    <p>Output from the first script section.</p>

    <h2>Second Script Section</h2>

    <p>Output from the second script section.</p>

    </body>

    </html>


Creating multiple code declaration blocks continued1

Creating Multiple Code Declaration Blocks (continued)

PHP Programming with MySQL, 2nd Edition

Figure 1-9 Output of a document with two PHP script sections


Case sensitivity in php

Case Sensitivity in PHP

  • Programming language constructs in PHP are mostly case insensitive<?php

    echo("<p>Explore <strong>Africa</strong>, <br>");

    Echo("<strong>South America</strong>, <br>");

    ECHO(" and <strong>Australia</strong>!</p>");

    ?>

  • But other parts of PHP are case sensitive. A good coding practice is to always write code as if it were case sensitive.


Adding comments to a php script

Adding Comments to a PHP Script

  • Comments are nonprinting lines placed in code that do not get executed, but provide helpful information, such as:

    • The name of the script

    • Your name and the date you created the program

    • Notes to yourself

    • Instructions to future programmers who might need to modify your work


Adding comments to a php script continued

Adding Comments to a PHP Script (continued)

  • Line comments hide a single line of code

    • Add // or # before the text

  • Block comments hide multiple lines of code

    • Add /* to the first line of code

    • And */ after the last character in the code


Adding comments to a php script continued1

Adding Comments to a PHP Script (continued)

PHP Programming with MySQL, 2nd Edition

<?php

/*

This line is part of the block comment.

This line is also part of the block comment.

*/

echo "<h1>Comments Example</h1>"; // Line comments can follow

code statements

// This line comment takes up an entire line.

# This is another way of creating a line comment.

/* This is another way of creating

a block comment. */

?>


Adding comments to a php script continued2

Adding Comments to a PHP Script (continued)

<?php

/*************************************************

Name: demo.php

Author: Jeremy Shafer

Purpose: Demonstrate different kinds of comments.

Revision Revised byComment

20130902jeremycreated file

**************************************************/

echo("<h1>Comments Example</h1>"); // Line comments can follow

code statements

// This line comment takes up an entire line.

# This is another way of creating a line comment.

/* This is another way of creating

a block comment. */

?>


Using variables and constants

Using Variables and Constants

PHP Programming with MySQL, 2nd Edition

  • The values stored in computer memory are called variables

  • The values, or data, contained in variables are classified into categories known as data types

  • The name you assign to a variable is called an identifier

  • An identifier must begin with a dollar sign ($), may not include a number as the first character, cannot include spaces, and is case sensitive


Displaying variables

Displaying Variables

  • To display a variable with the echo statement, pass the variable name to the echo statement without enclosing it in quotation marks:

    $VotingAge = 18;

    echo($VotingAge);

  • To display both text strings and variables, combine the strings together using the "." operator and then send them to the echo statement.

    echo("<p>The legal voting age is " . $VotingAge . "</p>");


Naming variables

Naming Variables

  • The following rules and conventions must be followed when naming a variable:

    • Variable names must begin with a dollar sign ($)

    • Variable names may contain uppercase and lowercase letters, numbers, or underscores (_).

    • The first character after the dollar sign must not be a number.

    • Variable names cannot contain spaces

    • Variable names are case sensitive

  • The name you assign to a variable is called an identifier


An illustration

An illustration


Which of these are valid php variable names

Which of these are valid PHP variable names?

  • $myCounter1

  • myCounter1

  • 1stCounter

  • $1stCounter

  • $_FirstCounter

  • $FirstCounter


Naming convention a suggestion

Naming convention … a suggestion

  • Hungarian Notation

  • Camel Case

    For example, instead of:

    $X = 0;

    Instead use:

    $intCounter = 0;


Declaring and initializing variables

Declaring and Initializing Variables

  • Specifying and creating a variable name is called declaring the variable

  • Assigning a first value to a variable is called initializing the variable

  • In PHP, you must declare and initialize a variable in the same statement:

    $variable_name = value;

  • Other languages require you to do be more detailed. For example, in C#:intvariable_x;x = 100;


Displaying variables1

Displaying Variables

PHP Programming with MySQL, 2nd Edition

Figure 1-11 Output from an echo statement

that is passed text and a variable


Displaying variables continued

Displaying Variables (continued)

PHP Programming with MySQL, 2nd Edition

  • The output of variable names inside a text string depends on whether the string is surrounded by double or single quotation marks

    Figure 1-12 Output of an echo statement that includes text and a variable surrounded by single quotation marks


Let s try it

Let's try it

  • Go back and edit helloworld.php

  • Notice the difference between:

    <?php

    $VotingAge = 18;

    echo("The legal voting age is $VotingAge");

    ?>

    And:

    <?php

    $VotingAge = 18;

    echo('The legal voting age is $VotingAge');

    ?>


Let s try it continued

Let's try it (continued)

  • My preferred approach is to ignore this feature and use the concatenation character.

    <?php

    $VotingAge = 18;

    echo("The legal voting age is " . $VotingAge);

    ?>

    Or:

    <?php

    $VotingAge = 18;

    echo('The legal voting age is ' . $VotingAge);

    ?>


Modifying variables

Modifying Variables

PHP Programming with MySQL, 2nd Edition

  • You can modify a variable's value at any point in a script

    $SalesTotal = 40;

    echo("<p>Your sales total is $$SalesTotal</p>");

    $SalesTotal = 50;

    echo("<p>Your new sales total is $$SalesTotal</p>");


Defining constants

Defining Constants

  • A constant contains information that does not change during the course of program execution

  • Constant names do not begin with a dollar sign ($)

  • Constant names use all uppercase letters

  • Use the define()function to create a constant

    define("CONSTANT_NAME", value);

  • The value you pass to the define() function can be a text string, number, or Boolean value


Let s try it1

Let's try it …

<?php

define("HOMEPAGE", 'http://www.santabiz.net');

echo("Please visit the home page. It can be found here: " . HOMEPAGE);

?>


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