Introduction to PHP

1
Introduction to PHP
2
What Is PHP? Stands for Personal Home Page
orPHP Hypertext

• Advantages of Using PHP to enhance Web pages
• Easy to use.
• Open source.
• Multiple platform.

3
How PHP Pages are Accessed and Interpreted
4
Getting Started with PHP

• To develop and publish PHP scripts all you need
  is
• A Web server with PHP built into it
• A client machine with a basic text editor and
  Internet connectionTextPad
• FTP or Telnet softwareat Conestoga, we are
  saving the files under C\Inetpub\wwwroot\name.p
  hp

5
Exploring the Basic PHP Development Process

• The basic steps you can use to develop and
  publish PHP pages are
• 1. Create a PHP script file and save it to a
  local disk using .php extension.
• 2. Use copy to copy the file to the server.
• 3. Access your file using a browser.

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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 lt?php tag and ends
  with ?gt.
• Between these tags is a singlePHP print
  statement.

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Alternative PHP Delimiters

• You can alternatively start your PHP scripts with
  the ltscriptgt tag as follows
• ltscript language"PHP"gt
• print ("A simple initial script")
• lt/scriptgt
• If have short_open_tag enabled in its
  configuration file, you can use lt? and ?gt.
• If asp_tags is enabled in the PHP configuration
  file, you can use lt and gt as delimiters.

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Proper Syntax

• If you have a syntax error then you have written
  one or more PHP statements that are grammatically
  incorrect in the PHP language.
• The print statement syntax

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If Use Improper Syntax

• Suppose you use the wrong syntax
• lt?php print ( A simple initial script)
• ?gt

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Php not giving errors

• If php is not giving errors
• Open the php.ini file under c\php5 in textpad,
  approx line 357
• Change the
• Display_errorson

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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 Documents
save as programName.php, to run
http//localhost/programName.php

• One way to use PHP is to embed PHP scripts
  within HTML tags in an HTML document.
• lthtmlgt
• ltheadgt
• lttitlegtHTML With PHP Embeddedlt/titlegt lt/headgt
• ltbodygt
• ltfont size5 color"blue"gtWelcome To My
  Pagelt/fontgt
• ltscript text phpgt
• print ("Using PHP is not hard")
• lt/scriptgt
• this is instead of Hello World
• lt/bodygtlt/htmlgt

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Would Output The Following ...
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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
  beoutputprint ("ltfont color\"blue\"gt")
• The above statement would output
• ltfont color"blue"gt

15
Using Comments with PHP Scripts

• Comments enable you to include descriptive text
  along with the PHP script.
• Comment lines are ignored when the script runs
  they do not slow down the run-time.
• Comments have two common uses.
• Describe the overall script purpose.
• Describe particularly tricky script lines.

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Using Comments with PHP Scripts

• Comment Syntax - Use //
• lt?php
• // This is a comment
• ?gt
• Can place on Same line as a statement
• lt?php
• print ("A simple initial script") //Output a
  line
• ?gt

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Example Script with Comments

• lthtmlgt ltheadgt
• lttitlegt Generating HTML From PHPlt/titlegt lt/headgt
• ltbodygt lth1gt Generating HTML From PHPlt/h1gt
• lt?php
• //
• // Example script to output HTML tags
• //
• print ("Using PHP has ltigtsome
  advantageslt/igt")
• print ("ltulgtltligtSpeedlt/ligtltligtEase of uselt/ligt
• ltligtFunctionalitylt/ligtlt/ulgt") //Output bullet
  list
• print ("lt/bodygtlt/htmlgt")
• ?gt

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Alternative Comment Syntax

• PHP allows a couple of additional ways to create
  comments.
• lt?php
• phpinfo() This is a built-in
  function
• ?gt
• Multiple line comments. lt?php
• /
• A script that gets information about the
• PHP version being used.
• /
• lt? phpinfo() ?gt

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Using PHP Variables

• Variables are used to store and access data in
  computer memory.
• A variable name is a label used within a script
  to refer to the data.

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Assigning New Values to Variables

• You can assign new values to variables
• days 3
• newdays 100
• days newdays
• At the end of these three lines, days and
  newdays both have values of 100.

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Selecting Variable Names

• You can select just about any set of characters
  for a variable name in PHP, but they must
• Use a dollar sign () as the first character
• Use a letter or an underscore character (_) as
  the second character.
• NoteTry to select variable names that help
  describe their function. For example counter is
  more descriptive than c or ctr.
• Must follow Conestoga Standards camelNotation

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Combining Variables and the print Statement

• That is, to print out the value of x, write the
  following PHP statement
• print ("x")
• The following code will output Bryant is 6 years
  old.
• age6
• print ("Bryant is age years old.")

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A Full Example ...

• lthtmlgt
• ltheadgt lttitlegtVariable Example lt/titlegt lt/headgt
• ltbodygt
• lt?php
• firstNum 12
• secondNum 356
• temp firstNum
• firstNum secondNnum
• secondNum temp
• print (First Number firstNum ltbrgtSecond Number
  secondNum")
• ?gt lt/bodygt lt/htmlgt

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Gives you ...
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Using Arithmetic Operators

• You can use operators such as a plus sign () for
  addition and a minus sign () for subtraction to
  build mathematical expressions.
• For example
• lt?php
• apples 12
• oranges 14
• totalFruit apples oranges
• print ("The total number of fruit is
  totalFruit")
• ?gt
• These PHP statements would output
• The total number of fruit is 26.

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Common PHP Numeric Operators
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Example

• lthtmlgt
• ltheadgt lttitlegtVariable Example lt/titlegt lt/headgt
• ltbodygt
• lt?php
• columns 20
• rows 12
• totalSeats rows columns
• ticketCost 3.75
• totalRevenue totalSeats ticketCost
• building_cost 300
• profit totalRevenue - buildingCost
• print ("Total Seats are totalSeats ltbrgt")
• print ("Total Revenue is totalRevenue
  ltbrgt")
• print ("Total Profit is profit")
• ?gt
• lt/bodygt lt/htmlgt

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Gives you ...
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WARNING Using Variables with Undefined Values
If you accidentally use a variable that does not
have a value assigned to it will have no value
(called a null value). When a variable with a
null value is used in an expression PHP, PHP may
not generate an error and may complete the
expression evaluation. For example, the
following PHP script will output x y4. lt?php
y 3 yy x 1 // x has a null value
print ("xx yy") ?gt
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Example

• lthtmlgt
• ltheadgt lttitlegtExpression Example lt/titlegt lt/headgt
• ltbodygt
• lt?php
• grade1 50
• grade2 100
• grade3 75
• average (grade1 grade2 grade3) / 3
• print ("The average is average")
• ?gt
• lt/bodygt lt/htmlgt

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Gives you ...
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Working with PHP String Variables

• Character strings are used in scripts to hold
  data such as customer names, addresses, product
  names, and descriptions.
• Consider the following example.
• name"Christopher"
• preference"Milk Shake"
• name is assigned Christopher and the variable
  preference is assigned Milk Shake.

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WARNING Be Careful Not to Mix Variable Types

• Be careful not to mix string and numeric variable
  types.
• For example, you might expect the following
  statements to generate an error message, but they
  will not. Instead, they will output y1.
• lt?php
• x "banana"
• sum 1 x
• print ("ysum")
• ?gt

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Using the Concatenate Operator. Vs

• 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 ("Fullnamefullname")

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TIP An Easier Way to Concatenate Strings

• You can also use double quotation marks to create
• concatenation directly,
• For example,
• Fullname "FirstName LastName"
• //This statement has the same effect as
• Fullname FirstName . " " . LastName

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The strlen() Function

• Most string functions require you to send them
  one or more arguments.
• Arguments are input values that functions use in
  the processing they do.
• Often functions return a value to the script
  based on the input arguments. For example

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The strlen() Function Example

• lt?php
• comments "Good Job"
• len strlen(comments)
• print ("Lengthlen")
• ?gt

This PHP script would output Length8.
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The trim() Function

• This function removes any blank characters from
  the beginning and end of a string. For example,
  consider the following script
• lt?php
• inName " Easter Bunny"
• name trim(inName)
• print ("namenamename")
• ?gt
• Would Print nameEaster BunnnyEaster Bunny

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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,
• lt?php
• inQuote "Now Is The Time"
• lower strtolower(inQuote)
• upper strtoupper(inQuote)
• print ("upperupper lowerlower")
• ?gt
• The above would output upperNOW IS THE TIME
  lowernow is the time.

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The substr() Function

• Substr has the following general format

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The substr() Function

• The substr() function enumerates character
  positions starting with 0 (not 1),
• For example, in the string Homer, the H would
  be position 0, the o would be position 1, the
  m position 2, and so on.
• For example, the following would output
• Month12 Day25.
• lt?php
• date "12/25/2009"
• month substr(date, 0, 2)
• day substr(date, 3, 2)
• print ("Monthmonth Dayday")
• ?gt

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The substr() Function

• As another example, consider the following use of
  the substr() function
• It does not include the third argument (and thus
  returns a substring from the starting position to
  the end of the search string).
• lt?php
• date "12/25/2099"
• year substr(date, 6)
• print ("Yearyear")
• ?gt
• The above script segment would output Year2099.

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Example with Buttons
lthtmlgt ltheadgt lttitlegt A Simple Form lt/titlegt
lt/headgt ltbodygt ltform actionnameOfThePHP.php"meth
od"post" gt Click submit to start our initial PHP
program. ltbrgt ltinput type"submit" value"Click
To Submit"gt ltinput type"reset" value"Erase and
Restart"gt lt/formgt lt/bodygt lt/htmlgt
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Gives you ...
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Receiving Input into PHP

• To receive HTML form input into a PHP script
• Use a PHP var name that matches the variable
  defined in the form elements name argument.
• For example, if form uses the following
• ltinput type"radio" name"contact" value"Yes"gt
• Then form-handling PHP script could use a
  variable called contact.
• If the user clicks the radio button, then
  contact would Yes

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To Receive Data from HTML

• _POST'name' ?gt.

Enclose in square bracket and then quotes
Name of HTML form variable (note do not use )
Special PHP Global variable. Technically it is an
associative array
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Another Example.

• Suppose your HTML form uses the following
• Enter email address ltinput type"text" size"16"
  maxlength"20" name"email"gt
• Then can receive input as follows
• lthtmlgt
• ltheadgtlttitlegt Receiving Input lt/titlegt lt/headgt
• ltbodygt
• lt?php
• email _POSTemail
• contact _POSTcontact
• ?gt
• ltfont size5gtThank You Got Your Input.lt/fontgt
• lt?php
• print ("ltbrgtYour email address is email")
• print ("ltbrgt Contact preference is contact")
• ?gt

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Gives you ...
49
Create Using textpad or Dreamweaver this html,
Save in C\inetpub\wwwroot\exercise?
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Receiving File in the same location, same name
with .php as the extension