PHP/Data Structure/Array Element

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Версия от 07:02, 26 мая 2010; Admin (обсуждение | вклад) (1 версия)
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Add elements to the end of an array

<?
$myarray = array("one", 2, "three");
$myarray[] = "the fourth element";
echo($myarray[3]);
?>



An array called $dinner with numeric keys

 
<?
$dinner[0] = "S";
$dinner[1] = "L";
$dinner[2] = "B";
?>



Array and scalar collision

 
<?
// This makes $vegetables an array
$vegetables["corn"] = "yellow";
// This makes $vegetables a scalar
$vegetables = "delicious";
// This makes $fruits a scalar
$fruits = 283;
// This makes $fruits an array and deletes its previous scalar value
$fruits["potassium"] = "banana";
?>



Array element navigation: next

<?
$major_city_info = array();
$major_city_info[0] = "A";
$major_city_info["A"] = "B";
$major_city_info[1] = "C";
$major_city_info["C"] = "D";
$major_city_info[2] = "E";
$major_city_info["E"] = "F";

function print_all_array($city_array)
{  
  $current_item = current($city_array);
  if ($current_item)
    print("$current_item<BR>");
  else
    print("There"s nothing to print");
  while($current_item = next($city_array))
    print("$current_item<BR>");
}
print_all_array($major_city_info);
print_all_array($major_city_info);// again, to see what happens
?>



Array element navigation: prev

<?
$major_city_info = array();
$major_city_info[0] = "A";
$major_city_info["A"] = "B";
$major_city_info[1] = "C";
$major_city_info["C"] = "D";
$major_city_info[2] = "E";
$major_city_info["E"] = "F";
function print_all_array_backwards($city_array)
{  
  $current_item = end($city_array); //fast-forward to last
  
  if ($current_item)
    print("$current_item<BR>");
  else
    print("There"s nothing to print");
  while($current_item = prev($city_array))
    print("$current_item<BR>");
}
print_all_array_backwards($major_city_info);
?>



Array index

 
<?php
  $arr = array();
  $arr[0] = "First ";
  $arr[1] = " PHP ";
  $arr[2] = "array";
  echo( $arr[0] . $arr[1] . $arr[2] );
?>
<hr>
<?php
  $mo = array( "Jan ", "Feb ", "Mar " );
  $dy = array( "21 ", "22 ", "23 " );
  $yr = array( "2005", "2006", "2007" );
    
  echo( $mo[1] . $dy[0] . $yr[1] );
?>



Arrays Demo

 
<?php
$weekdays[] = "Monday";
$weekdays[] = "Tuesday";
?>
<?php
$weekdays[0] = "Monday";
$weekdays[1] = "Tuesday";
?>
<?php
$weekdays[0] = "Monday";
$weekdays[1] = "Tuesday";
$weekdays[3] = "Wednesday";
?>



Assign elements from array to variables

 
<?php 
$scores = array(88, 75); 
@list($maths, $english, $history) = $scores; 
@printf("<p>Maths: %d; English: %d; History: %d; Biology: %d.</p>\n", $maths, $english, $history, $biology); 
?>



Assigning Array Values

 
<?php
    function assign_key() {
        return "d";
    }
    $foo["a"] = 1;
    $foo["b"] = 2;
    $foo["c"] = 3;
    $foo[assign_key()] = 4;    /* Assigned the key value "d" */
?>



Autogeneration of Array Indexes

 
<?php
    $foo[] = "Value 1";        /* Assigned key 0 */
    $foo[] = "Value 2";        /* Assigned key 1 */
    $foo[5] = "Value 3";       /* Assigned key 5 */
    $foo[] = "Value 4";        /* Assigned key 6 */
?>



Changing array values

 
<html>
 <head>
  <title>Changing array values</title>
 </head>
 <body>
 <?php
  $arr = array( "Red ", "Green ", "Blue" );
  echo( $arr[0] . $arr[1] . $arr[2] . "<hr>" );
  $arr[0] = 44;
  $arr[1] = 12.5;
  $arr[2] = $arr[0] + $arr[1];
    
  echo( "$arr[0] + $arr[1] = $arr[2]" );
 ?>
 </body>
</html>



Comparing Arrays: equality, identity, and the difference

 
<?php 
function array_eq_ident($arr1, $arr2) { 
    printf("<p>The two arrays are %sequal.</p>\n", $arr1 == $arr2 ? "" : "not "); 
    printf("<p>The two arrays are %sidentical.</p>\n", $arr1 === $arr2 ? "" : "not ");
} 
$dogs = array("A" => "C", "B" => "D", "X" => "Z", "Q" => "T"); 
$pups = array("A" => "C", "B" => "D", "X" => "Z", "Q" => "T"); 
array_eq_ident($dogs, $pups); 
?>



Display an array

 
<?php
  function array_display($array, $pre=FALSE)
  {
    $tag = $pre ? "pre" : "p";
    printf("<%s>%s</%s>\n", $tag, var_export($array, TRUE), $tag);
  }
  
  function change(&$element, $key, $mark)
  {
    $element = "$mark$key$mark, the $element";
  }
  $dogs = array("A" => "AA", "Bud" => "BB");
  array_display($dogs, TRUE);
  array_walk($dogs, "change", "*");
  array_display($dogs, TRUE);
?>



Elements of the enumerated array are numbers

 <?php
  $sortnumbers []= 10000;
  $sortnumbers []= 10;
  $sortnumbers []= 100;
  $sortnumbers []= 1000;
  $sortnumbers []= 1;
  sort ($sortnumbers);
  foreach ($sortnumbers as $val) {
    echo "$val", "\n";
  }
 ?>



Operating on array elements

 
<?
$dishes["A"] = 12;
$dishes["A"]++;
$dishes["B"] = 3;
$dishes["total"] = $dishes["A"] + $dishes["B"];
if ($dishes["total"] > 15) {
    print "You ate a lot: ";
}
print "You ate " . $dishes["A"];
?>



Reference Array by index

<?
$myarray = array("one", 2, "three");
echo($myarray[0]);
echo($myarray[1]);
echo($myarray[2]);

?>



Use the index in square brackets to create new elements and or assign values

<?
$myarray = array("one", 2, "three");
$myarray[1] = "two";
$myarray[3] = "four";
echo($myarray[0]);
echo($myarray[1]);
echo($myarray[2]);
echo($myarray[3]);
?>
Источник — «http://wbex.ru/index.php?title=PHP/Data_Structure/Array_Element&oldid=185»