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PHP. Functions Composite Types. 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)

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Php

PHP

Functions

Composite Types


Functions

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


Variable scope

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


Compound types in php

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


Arrays

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


Creating an array

Creating an array

  • Create dynamically by assigning values to elements

    • $veggie['corn'] = 'yellow';

    • $dinner[0] = 'Lemon Chicken';

  • Use the Array constructor

    • $veggie = array( 'corn' => 'yellow', 'beet' => 'red', 'carrot' => 'orange');


Creating a numeric array

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';


Using arrays

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);


Sorting arrays

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


Looping with arrays

Looping with arrays

  • Use foreach to loop through elements of array

    foreach( $meal as $key => $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


Classes and objects

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


Sample class definition

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) {

$this->items[$artnr] += $num;}

// Take $num articles of $artnr out of the cart

function remove_item($artnr, $num) {

if ($this->items[$artnr] > $num) {

$this->items[$artnr] -= $num;

return true;

} elseif ($this->items[$artnr] == $num) {

unset($this->items[$artnr]);

return true;

} else { return false; }

}


Constructors

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')

      { $catalogNum=$id;

      $price = $cost; }

      ÔÇŽ }


Using objects

Using Objects

  • Use new to create objects

    • $myItem = new Item( 'AB234', 3.95);

  • Access methods and properties with -> operator

    • $charge = $myItem->price;


Sources

Sources

  • Learning PHP 5 by David Sklar

  • Programming PHP by Rasmus Ledorf and Kevin Tatroe

  • PHP home page

    • http://www.php.net/


  • Login