PHP/Data Structure/array

Accessing Array Elements

 
<?
$my_array = array(); 
$pets = array("A", "B", "C", "D"); 
$person = array("R", "W", 24, "CA"); 
$customer = array("first" => "R", "last" => "W", "age" => 24, "state" => "CA"); 
print "<p>"$pets[0]".</p>\n"; 
print "<p>$person[2].</p>\n"; 
print "<p>{$customer["age"]}.</p>\n"; 
?>

A list of numbers using an array variable

 
<?php 
$Inventory = array(1,2,3); 
print "$Inventory[0]<br>\n"; 
print "$Inventory[1]<br>\n"; 
print "$Inventory[2]<br>\n"; 
print "<p>An array variable!"; 
?>

Arrays

 
<?
    $myarray = array("Apples", "Oranges", "Pears");
    $size = count($myarray);
    print_r($myarray);
?>

Converting an object to an array will convert properties to elements of the resulting array

 
<?php 
class myclass { 
    public $name; 
    public $address; 
    private $age; 
    function SetAge($age) { 
        $this->age = $age; 
    } 
} 
$obj = new myclass; 
$obj->name = "John"; 
$obj->address = "Main Street"; 
$obj->SetAge(47); 
$arr = (array)$obj; 
print_r($arr); 
?>

Create an array

 
<?
$fruits = array (
    "fruits" => array("a"=>"orange", "b"=>"banana", "c"=>"apple"),
    "numbers" => array(1, 2, 3, 4, 5, 6),
    "holes" => array("first", 5 => "second", "third")
);
?>

Creates an array with keys 0 through 3

 
<?php
    $myarray = array("a", "b", "c", "d");
?>

Creating arrays with array()

 
$vegetables = array("corn" => "yellow",
                    "beet" => "red",
                    "carrot" => "orange");
$dinner = array(0 => "S",
                1 => "L",
                2 => "B");
$computers = array("t" => "A",
                   2600 => "B",
                   "A" => "C");
?>

Creating multidimensional arrays with array()

 
<?
$meals = array("breakfast" => array("A","C"),
               "lunch"     => array("B", "E"),
               "snack"     => array("C","F"));
$lunches = array( array("Chicken","Eggplant","Rice"),
                  array("Eggplant","Tofu"));
$flavors = array("Japanese" => array("hot" => "1",
                                     "salty" => "2"),
                 "Chinese"  => array("hot" => "3",
                                     "pepper-salty" => "4"));
?>

Creating numeric arrays with array()

 
<?
$dinner = array("A",
                "B",
                "C");
print "I want $dinner[0] and $dinner[1].";
?>

Demonstrate the Difference Between the Array "+" Operator and a True Array Union

 
<?php
$first = array("e", "h", "r", "j", "b");
$last = array("w", "e", "c");
$plus_union = $last + $first;
echo "<p>";
foreach ($plus_union as $v) { echo "{$v} "; }
echo "</p>\n";
$union = array_unique(array_merge($first, $last));
echo "<p>";
foreach ($union as $v) { echo "{$v} "; }
echo "</p>\n";
?>

Queue Handling Library

 
<?php
function &queue_initialize() {
    $new = array();
    return $new;
}
function queue_destroy(&$queue) {
    unset($queue);
}
function queue_enqueue(&$queue, $value) {
    $queue[] = $value;
}
function queue_dequeue(&$queue) {
    return array_shift($queue);
}
function queue_peek(&$queue) {
    return $queue[0];
}
function queue_size(&$queue) {
    return count($queue);
}
function queue_rotate(&$queue) {
    $queue[] = array_shift($queue);
}
$myqueue =& queue_initialize();
queue_enqueue($myqueue, "Opal");
queue_enqueue($myqueue, "Dolphin");
queue_enqueue($myqueue, "Pelican");
echo "<p>Queue size is: ", queue_size($myqueue), "</p>";
echo "<p>Front of the queue is: ", queue_peek($myqueue), "</p>";
queue_rotate($myqueue);
echo "<p>Removed the element at the front of the queue: ", queue_dequeue($myqueue), "</p>";
queue_destroy($myqueue);
?>

Setting up an associative array is similarly easy

 
<? 
$myassocarray = array ("mykey" => "myvalue", "another" => "one"); 
while ($element = each ($myassocarray)) { 
  echo "Key - " . $element["key"] . " and Value - " . $element["value"] . "<br />"; 
}
?>

Stack Handling Library

 
<?php
function &stack_initialize() {
    $new = array();
    return $new;
}
function stack_destroy(&$stack) {
    unset($stack);
}
function stack_push(&$stack, $value) {
    $stack[] = $value;
}
function stack_pop(&$stack) {
    return array_pop($stack);
}
function stack_peek(&$stack) {
    return $stack[count($stack)-1];
}
function stack_size(&$stack) {
    return count($stack);
}
function stack_swap(&$stack) {
    $n = count($stack);
    if ($n > 1) {
        $second = $stack[$n-2];
        $stack[$n-2] = $stack[$n-1];
        $stack[$n-1] = $second;
    }
}
function stack_dup(&$stack) {
    $stack[] = $stack[count($stack)-1];
}
$mystack =& stack_initialize();
stack_push($mystack, 73);
stack_push($mystack, 74);
stack_push($mystack, 5);
stack_dup($mystack);
echo "<p>Stack size is: ", stack_size($mystack), "</p>";
echo "<p>Popped off the value: ", stack_pop($mystack), "</p>";
stack_swap($mystack);
echo "<p>Current top element is: ", stack_peek($mystack), "</p>";
stack_destroy($mystack);
?>

Using the array() Function

 
<?php
    /* Arrays $foo and $bar are equivalent arrays */
    $foo = array("a" => 1, "b" => 2, "c" => 3);
    $bar["a"] = 1;
    $bar["b"] = 2;
    $bar["c"] = 3;
?>

Using the array function to create an array of weekdays

 
<?php
$weekdays = array("Monday",
                  "Tuesday",
                  "Wednesday",
                  "Thursday",
                  "Friday",
                  "Saturday",
                  "Sunday");
?>