PHP

1
PHP

• Functions
• Composite Types

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Functions

• Declaration
• function functionName(paramList)
• / code goes here /
• paramList is comma-separated list of param names
  with optional default values
• use return to return a value
• Calling a function
• functionName( argList)
• argList is comma-separated list of expressions -
  number must match declaration

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Variable scope

• Variables defined outside of any function are
  global
• Variables defined inside a function are local to
  the function (as are parameters)
• Using global variables in a function
• GLOBALS is array containing all global variables
• global keyword

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Compound Types in PHP

• PHP has two compound types
• Arrays -arrays in PHP are really ordered maps
• multi-dimensional arrays are arrays whose
  elements are arrays
• Objects - variables whose type is defined by a
  class

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Arrays

• An array consists of a collection of elements
• each element has a key and a value (like a hash
  table)
• arrays with only numeric keys are a special case
• you can use arrays with numeric keys the same way
  you do an array in C or Java

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Creating an array

• Create dynamically by assigning values to
  elements
• veggie'corn' 'yellow'
• dinner0 'Lemon Chicken'
• Use the Array constructor
• veggie array( 'corn' gt 'yellow', 'beet' gt
  'red', 'carrot' gt 'orange')

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Creating a numeric array

• Use array with just a list of values
• keys will automatically be numbers (starting from
  0)
• dinner ('Sweet Corn and Asparagus', 'Lemon
  Chicken', 'Spicy Eggplant')
• Add new elements to end of list by assigning with
  no index
• dinner 'Braised Bamboo fungus'

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Using arrays

• count(arrayName) gives the number of elements in
  the array
• implode(delim, array) creates a string from an
  array
• menu implode( ', ', dinner)
• explode(delim, string) creates a numeric array
  from a string
• dinner explode( ', ', menu)

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Sorting arrays

• The array elements will be rearranged by these
  methods
• sort()/rsort() sort by element values
  (ascending/descending)
• asort()/arsort() sort by element value, keeping
  keys and values together
• ksort()/krsort() sort by key, keeping keys and
  values together

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Looping with arrays

• Use foreach to loop through elements of array
• foreach( meal as key gt value)
• print "key value\n"
• foreach( dinner as dish)
• print "You can eat dish.\n"
• foreach goes through elements in order they were
  added to array
• not necessarily numeric order

11
Classes and Objects

• PHP supports object-oriented programming
• Class is a template describing both data and
  operations
• Method is a function defined in a class
• Property is a variable defined in a class
• Constructor is used to create instances (objects)
• Static method doesn't need an object

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Sample Class definition

• class Cart
• var items // Items in our shopping cart
• // Add num articles of artnr to the cart
• function add_item(artnr, num)
• this-gtitemsartnr num
• // Take num articles of artnr out of the cart
• function remove_item(artnr, num)
• if (this-gtitemsartnr gt num)
• this-gtitemsartnr - num
• return true
• elseif (this-gtitemsartnr num)
• unset(this-gtitemsartnr)
• return true
• else return false

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Constructors

• Constructor is a method with the same name as the
  class
• Use it to initialize properties
• class Item
• var catalogNum, price
• function Item(id'none', cost'0.0')
• catalogNumid
• price cost

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Using Objects

• Use new to create objects
• myItem new Item( 'AB234', 3.95)
• Access methods and properties with -gt operator
• charge myItem-gtprice

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Sources

• Learning PHP 5 by David Sklar
• Programming PHP by Rasmus Ledorf and Kevin Tatroe
• PHP home page
• http//www.php.net/