PHP

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PHP

• Language Structure and Programming Techniques

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PHP

• Serverside programming language
• Designed for quick development of HTML based
  dynamic web pages
• Server side scripts embedded in HTML page
• lt?php . ?gt
• Elements of C, Java and Perl

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PHP HelloWorld

• Use echo to output information
• echo Hello World
• Either single or double quotes
• lthtmlgtltheadgt
• lttitlegtPHP Hello Worldlt/titlegt
• lt/headgt
• ltbodygt
• lt?php echo 'lth2gtHello Worldlt/h2gt' ?gt
• lt/bodygt
• lt/htmlgt

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PHP Variables

• Variables in PHP are dynamically typed
• Variable names
• begin with a sign.
• next character not a number
• E.g.
• value 1
• value2 hello
• Reference variable assigned using
• value3 value2

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PHP Operators

• ,,,-,/,,,,!,,--,,/,,gt,lt,gt,
  lt,,,,
• All similar to C
• Additionally
• , !
• Identical, as well as having equal value they are
  the same type
• _at_
• Error suppression command
• Back tick operator to execute shell comands,
  similar to shel_exec(). Watch out for variations
  on different platforms, windows vs unix
• .
• String concatenation operator
• Fullname firstname. .lastname

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PHP Arrays

• Arrays in PHP are associative arrays
• E.g.
• details array ( namegt Chris, deptgt
  IIMS, citygt Auckland)
• Access array elements using keyword
• echo detailsname
• Associate index can be numbers or strings
• E.g. Auto indexing
• myArray array(1, 2, 3, 4, 5, 10gt1, 5gt2, 20,
  3 gt 25)
• print_r(myArray) gives
• Array ( 0 gt 1 1 gt 2 2 gt 3 3 gt 25 4
  gt  5 10 gt 1 5 gt 2 11 gt 20 )

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PHP Functions

• Functions declared using function keyword
• function myHello() echo hello
• Functions can take parameters (passed as values)
• function myHello2(x) echo hello x
• Functions can return values
• function myAdd(x,y) return xy
• Functions can take parameters by reference
• function myRef(x) xHello

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More PHP Functions

• Functions can return references
• function myReturnRef()
• global hello return hello
• Functions can have default parameter values
• function myHello3(xChris)
• echo hello x

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PHP Classes

• Object Oriented Programming in PHP
• Declare classes using class keyword
• class details
• var name var city
• function details(n,c)
• namencityc
• Instansiate classes using new keyword
• myDetails new details(Chris, Auckland)

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PHP Structured Programming Constructs

• if, else, switch case , break, continue
• Similar to C
• elseif
• Different syntax to C, same semantics
• while .., do .. while, for ..
• All similar to C
• foreach ( array as val) .
• foreach ( array as keygtval) .
• Iterates through named array
• Note acts on a copy of the array

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Additional PHP Constructs

• require(.)
• Includes file specified, terminates on errors
• include()
• Includes file specified, gives warning on errors
• require_once(.)
• Includes file specified only if it has not
  already been included, terminates on errors
• include_once(.)
• Includes file specified only if it has not
  already been included, gives warning on errors

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PHP Built in Variables

• GLOBALS
• _SERVER
• _GET
• _POST
• _COOKIE
• _FILES
• _ENV
• _REQUEST
• _SESSION
• NOTE old versions specify HTTP_XXXXX_VARS

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PHP Processing Form Variables

• Extract submitted form variables from
• _GET
• _POST
• Depending on the submission method
• _REQUEST also contains variables but may
  violate security by using wrong method compared
  to the application design
• Submitted files can be extracted from
• _FILES

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PHP Cookie Variables

• setcookie(string name, string value, int expire,
  string path, string domain, int secure)
• Should be the first line of a HTML file (inside
  lt?php. ?gt
• Needs to be sent as part of HTTP header so cant
  be after any text (even blank spaces)
• Expiry time
• time()3600
• In one hour etc
• Path
• Default is /, add more to be specific to
  application /myApp/
• Domain
• Restrict cookie access to current domain e.g.
  .massey.ac.nz
• Secure
• Whether the cookie is sent over a secure
  connection

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PHP Cookies cont.

• if(!isset(COOKIE_SET))
• setcookie("test", newCookie")
• header("Location _SERVER'SCRIPT_NAME
  '?COOKIE_SET1")
• exit
• Need to make sure cookie is set before reading a
  cookie. If the cookie has only just been set, the
  page must be reloaded before the cookie can be
  read
• setcookie("test)
• Delete a cookie by calling set cookie with just
  the name
• Read the cookie values from
• _COOKIE variable

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PHP Sessions

• Sessions in PHP can be used even if cookies are
  disabled
• session_start()
• Called before starting to use any session
  functions, note use before any content is sent
• header("Cache-control private")
• Used to enable correct performance when returning
  to submission forms
• _SESSION'name' name
• Specify a value for a session variable

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PHP Sessions cont

• unset(_SESSION'name')
• Remove a session variable
• session_destroy()
• Terminate a session, not normally done, leave to
  timeout.

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Summary
Main points to remember PHP Language
Constructs Built in PHP variables Processing
Forms Cookies Sessions