array()

(PHP 4, PHP 5, PHP 7)

新建一个数组

说明

array([mixed $...] ): array

创建一个数组。关于数组是什么的信息请阅读数组一节。

参数

语法“index => values”，用逗号分开，定义了索引和值。索引可以是字符串或数字。如果省略了索引，会自动产生从 0 开始的整数索引。如果索引是整数，则下一个产生的索引将是目前最大的整数索引+ 1。注意如果定义了两个完全一样的索引，则后面一个会覆盖前一个。

在最后一个定义的数组项目之后加一个逗号虽然不常见，却是合法的语法。

返回值

返回根据参数建立的数组。参数可以用=>运算符给出索引。关于数组是什么的信息请阅读数组一节。

范例

下面的例子演示了怎样建立一个二维数组，怎样给相应的数组指定键名，以及怎样在普通数组中略过和继续数字索引。

Example #1array()例子

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

Example #2array()的自动索引

<?php
$array = array(1, 1, 1, 1,  1, 8 => 1,  4 => 1, 19, 3 => 13);
print_r($array);
?>

以上例程会输出：

Array
(
    [0] => 1
    [1] => 1
    [2] => 1
    [3] => 13
    [4] => 1
    [8] => 1
    [9] => 19
)

注意索引 3 被定义了两次，保留了最后的值 13。索引 4 在索引 8 之后定义，下一个自动生成的索引（值为 19 那个）为 9，因为最大的索引是 8。

本例建立了从 1 开始的数组。

从 1 开始索引的array()

<?php
$firstquarter = array(1 => 'January', 'February', 'March');
print_r($firstquarter);
?>

以上例程会输出：

Array
(
    [1] => January
    [2] => February
    [3] => March
)

在 Perl 中，可以访问在双引号内的数组的值。但在 PHP 中需要将数组用花括号括起来。

访问双引号内的数组

<?php
$foo = array('bar' => 'baz');
echo "Hello {$foo['bar']}!"; // Hello baz!
?>

注释

Note:

array()是一个语言结构，用于字面上表示数组，不是常规的函数。

参见

• array_pad()以指定长度将一个值填充进数组
• list()把数组中的值赋给一组变量
• count()计算数组中的单元数目，或对象中的属性个数
• range()根据范围创建数组，包含指定的元素
• foreach
• The array type

As of PHP 5.4.x you can now use 'short syntax arrays' which eliminates the need of this function.
'short syntax array'
<?php
  $a = [1, 2, 3, 4];
  print_r($a);
?>
The above example will output:
Array
(
  [0] => 1
  [1] => 2
  [2] => 3
  [3] => 4
)
'short syntax associative array'
<?php
  $a = ['one' => 1, 'two' => 2, 'three' => 3, 'four' => 4];
  print_r($a);
?>
The above example will output:
Array
(
  [one] => 1
  [two] => 2
  [three] => 3
  [four] => 4
)

If you need, for some reason, to create variable Multi-Dimensional Arrays, here's a quick function that will allow you to have any number of sub elements without knowing how many elements there will be ahead of time. Note that this will overwrite an existing array value of the same path.
<?php
// set_element(array path, mixed value)
function set_element(&$path, $data) {
  return ($key = array_pop($path)) ? set_element($path, array($key=>$data)) : $data;
}
?>
For example:
<?php
echo "<pre>";
$path = array('base', 'category', 'subcategory', 'item');
$array = set_element($path, 'item_value');
print_r($array);
echo "</pre>";
?>
Will display:
Array
(
  [base] => Array
    (
      [category] => Array
        (
          [subcategory] => Array
            (
              [item] => item_value
            )
        )
    )
)

The following function (similar to one above) will render an array as a series of HTML select options (i.e. "<option>...</option>"). The problem with the one before is that there was no way to handle <optgroup>, so this function solves that issue.
function arrayToSelect($option, $selected = '', $optgroup = NULL)
{
  $returnStatement = '';
  if ($selected == '') {
    $returnStatement .= '<option value="" selected="selected">Select one...</option>';
  }
  if (isset($optgroup)) {
    foreach ($optgroup as $optgroupKey => $optgroupValue) {
      $returnStatement .= '<optgroup label="' . $optgroupValue . '">';
      foreach ($option[$optgroupKey] as $optionKey => $optionValue) {
        if ($optionKey == $selected) {
          $returnStatement .= '<option selected="selected" value="' . $optionKey . '">' . $optionValue . '</option>';
        } else {
          $returnStatement .= '<option value="' . $optionKey . '">' . $optionValue . '</option>';
        }
      }
      $returnStatement .= '</optgroup>';
    }
  } else {
    foreach ($option as $key => $value) {
      if ($key == $selected) {
        $returnStatement .= '<option selected="selected" value="' . $key . '">' . $value . '</option>';
      } else {
        $returnStatement .= '<option value="' . $key . '">' . $value . '</option>';
      }
    }
  }
  return $returnStatement;
}
 So, for example, I needed to render a list of states/provinces for various countries in a select field, and I wanted to use each country name as an <optgroup> label. So, with this function, if only a single array is passed to the function (i.e. "arrayToSelect($stateList)") then it will simply spit out a bunch of "<option>" elements. On the other hand, if two arrays are passed to it, the second array becomes a "key" for translating the first array.
Here's a further example:
$countryList = array(
  'CA'    => 'Canada',
  'US'    => 'United States');
$stateList['CA'] = array(
  'AB'    => 'Alberta',
  'BC'    => 'British Columbia',
  'AB'    => 'Alberta',
  'BC'    => 'British Columbia',
  'MB'    => 'Manitoba',
  'NB'    => 'New Brunswick',
  'NL'    => 'Newfoundland/Labrador',
  'NS'    => 'Nova Scotia',
  'NT'    => 'Northwest Territories',
  'NU'    => 'Nunavut',
  'ON'    => 'Ontario',
  'PE'    => 'Prince Edward Island',
  'QC'    => 'Quebec',
  'SK'    => 'Saskatchewan',
  'YT'    => 'Yukon');
$stateList['US'] = array(
  'AL'    => 'Alabama',
  'AK'    => 'Alaska',
  'AZ'    => 'Arizona',
  'AR'    => 'Arkansas',
  'CA'    => 'California',
  'CO'    => 'Colorado',
  'CT'    => 'Connecticut',
  'DE'    => 'Delaware',
  'DC'    => 'District of Columbia',
  'FL'    => 'Florida',
  'GA'    => 'Georgia',
  'HI'    => 'Hawaii',
  'ID'    => 'Idaho',
  'IL'    => 'Illinois',
  'IN'    => 'Indiana',
  'IA'    => 'Iowa',
  'KS'    => 'Kansas',
  'KY'    => 'Kentucky',
  'LA'    => 'Louisiana',
  'ME'    => 'Maine',
  'MD'    => 'Maryland',
  'MA'    => 'Massachusetts',
  'MI'    => 'Michigan',
  'MN'    => 'Minnesota',
  'MS'    => 'Mississippi',
  'MO'    => 'Missouri',
  'MT'    => 'Montana',
  'NE'    => 'Nebraska',
  'NV'    => 'Nevada',
  'NH'    => 'New Hampshire',
  'NJ'    => 'New Jersey',
  'NM'    => 'New Mexico',
  'NY'    => 'New York',
  'NC'    => 'North Carolina',
  'ND'    => 'North Dakota',
  'OH'    => 'Ohio',
  'OK'    => 'Oklahoma',
  'OR'    => 'Oregon',
  'PA'    => 'Pennsylvania',
  'RI'    => 'Rhode Island',
  'SC'    => 'South Carolina',
  'SD'    => 'South Dakota',
  'TN'    => 'Tennessee',
  'TX'    => 'Texas',
  'UT'    => 'Utah',
  'VT'    => 'Vermont',
  'VA'    => 'Virginia',
  'WA'    => 'Washington',
  'WV'    => 'West Virginia',
  'WI'    => 'Wisconsin',
  'WY'    => 'Wyoming');
...
<select name="state" id="state"><?php echo arrayToSelect($stateList,'',$countryList) ?></select>
<select name="country" id="country"><?php echo arrayToSelect($countryList,'US') ?></select>

If you need to add an object as an array key, for example an object from Simple XML Parser, you can use the following.
File.XML
<?xml version="1.0" encoding="UTF-8"?>
<Settings type="General">
 <Setting name="SettingName">This This This</Setting>
</Settings>
The script:
<?php
$raw = $xml = new SimpleXMLElement('File.XML');
foreach($raw->Setting as $A => $B)
{    
  // Set Array From XML
  $Setting[(string) $B['name']] = (string) $B[0];
}
?>
By telling the key to read the object as a string, it will let you set it.
Hope this helps someone out!

"Quick and dirty" class to get an offset of multidimensional array by given path (sorry, that without comments).
<?php
  class ArrayAsPathException extends Exception {} 
  class ArrayAsPath {
    protected
      $data = array(),
      $separator = '.';
    public function __construct (array $data = array()) {
      $this->data = $data;
    }
    public function set ($value, $path = null) {
      if (!isset($path)) {
        $this->data = $value;
      }
      $separator = $this->separator;
      $pathtoken = strtok($path, $separator);
      $code = '';
      $pices = '[\''.$pathtoken.'\']';
      while ($pathtoken !== false) {
        if (($pathtoken = strtok($separator)) !== false) {
          $code .= 'if (!isset($this->data'.$pices.')) $this->data'.$pices.' = array(); ';
          $pices .= '[\''.$pathtoken.'\']';
        } else {
          $code .= 'return $this->data'.$pices.' = $value;';
        }
      }
      return eval($code);
    }
    public function get ($path = '', $default = null) {
      $result = $this->data;
      $separator = $this->separator;
      $pathtoken = strtok($path, $separator);
      while ($pathtoken !== false) {
        if (!isset($result[$pathtoken]) || is_string($result)) {
          if (isset($default)) {
            return $default;
          }
          throw new ArrayAsPathException ('Can\'t find "'.$pathtoken.'" in "'.$path.'"');
        }
        $result = $result[$pathtoken];
        $pathtoken = strtok($separator);
      }
      return $result ? $result : $default;
    }
    public function has ($path) {
      $result = $this->data;
      $separator = $this->separator;
      $pathtoken = strtok($path, $separator);
      while ($pathtoken !== false) {
        if (!isset($result[$pathtoken]) || is_string($result)) {
          return false;
        }
        $result = $result[$pathtoken];
        $pathtoken = strtok($separator);
      }
      return true;
    }
    public function setSepatator ($separator) {
      $this->separator = $separator;
    }
    public function getSeparator ($separator) {
      return $this->separator;
    }
  }
?>
Code:
<?php
  $params = new ArrayAsPath;
  $params->set(array(
    'foo' => array(
      'bar' => array(
        'item' => 'Value'
      )
    )
  ));
  try {
    $params->set('test', 'foo.bar.far.new');
    printf(
      'Array:<pre>%s</pre>
      foo.bar.item:<pre>%s</pre>
      foo.bar.far:<pre>%s</pre>
      foo.bar.far.new<pre>%s</pre>',
      var_export($params->get(), true),
      var_export($params->get('foo.bar.item'), true),
      var_export($params->get('foo.bar.far'), true),
      var_export($params->get('foo.bar.far.new'), true)
    );
  } catch (ArrayAsPathException $e) {
    echo 'Oops! It seems that something is wrong. '.$e->getMessage();
  }
?>
Will display:
Array:
array (
 'foo' => 
 array (
  'bar' => 
  array (
   'item' => 'Value',
   'far' => 
   array (
    'new' => 'test',
   ),
  ),
 ),
)
foo.bar.item:
'Value'
foo.bar.far:
array (
 'new' => 'test',
)
foo.bar.far.new:
'test'

I encountered the following but didn't see it documented/reported anywhere so I'll just mentioned it here.
As written in the manual:
"When index is omitted, an integer index is automatically generated, starting at 0. If index is an integer, next generated index will be the biggest integer index + 1".
This generated index has always the largest integer used as a key so far. So adding $a[5] = 'foo'; after an $a[10] = 'bar'; will not force the next generated index to be 6 but to be 11 as 10 was the highest index encountered until here.
Anyway, the following can happen:
<?php
$max_int = 2147483647; // Max value for integer on a 32-bit system
$arr = array();
$arr[1] = 'foo'; // New generated index will be 2
$arr[ $max_int ] = 'bar'; // Caution: Next generated index will be -2147483648 due to the integer overflow!
$arr[0] = 'bar'; // The highest value should be 2147483648 but due to the i-overflow it is -2147483648 so current index 0 is larger. The new generated index therefore is 1!
$arr[] = 'failure'; // Warning: Cannot add element to the array as the next element is already occupied.
?>

Notice that you can also add arrays to other arrays with the $array[] "operator" while the dimension doesn't matter.
Here's an example:
$x[w][x] = $y[y][z];
this will give you a 4dimensional assosiative array.
$x[][] = $y[][];
this will give you a 4dimensional non assosiative array.
So let me come to the point. This get interessting for shortening things up. For instance:
<?php
    foreach ($lines as $line){
      if(!trim($line)) continue;
      $tds[] = explode("$delimiter",$line);
    }
?>

<?php
// changes any combination of multiarray elements and subarrays
// into a consistent 2nd level multiarray, tries to preserves keys
function changeMultiarrayStructure($multiarray, $asc = 1) {
 if ($asc == 1) { // use first subarrays for new keys of arrays
  $multiarraykeys = array_reverse($multiarray, true);
 } else { // use the last array keys
  $multiarraykeys = $multiarray; // use last subarray keys
 } // end array reordering
 $newarraykeys = array(); // establish array
 foreach ($multiarraykeys as $arrayvalue) { // build new array keys
  if (is_array($arrayvalue)) { // is subarray an array
   $newarraykeys = array_keys($arrayvalue) + $newarraykeys;
  } // if count(prevsubarray)>count(currentarray), extras survive 
 } // end key building loop
 foreach ($multiarray as $newsubarraykey => $arrayvalue) {
  if (is_array($arrayvalue)) { // multiarray element is an array
   $i = 0; // start counter for subarray key
   foreach ($arrayvalue as $subarrayvalue) { // access subarray
    $newmultiarray[$newarraykeys[$i]][$newsubarraykey] = $subarrayvalue;
    $i++; // increase counter
   } // end subarray loop
  } else { // multiarray element is a value
   foreach ($newarraykeys as $newarraykey) { // new subarray keys
    $newmultiarray[$newarraykey][$newsubarraykey] = $arrayvalue;
   } // end loop for array variables
  } // end conditional
 } // end new multiarray building loop
 return $newmultiarray;
}
// will change 
$old = array('a'=>1,'b'=>array('e'=>2,'f'=>3),'c'=>array('g'=>4),'d'=>5);
// to 
$new = array('e'=>array('a'=>1,'b'=>2,'c'=>4,'d'=>5),
 'f'=>array('a'=>1,'b'=>3,'d'=>5));
// note: if $asc parameter isn't default, last subarray keys used 
?>
The new key/value assignment pattern is clearer with bigger arrays.
I use this to manipulate input/output data from my db. Enjoy.

Chek this out!!!. Suppose that you want to create an array like the following:
<?php
 $arr1 = (
  0 => array ("customer"=>"Client 1","Item a"),
  1 => array ("customer"=>"Client 2","Item b")
 );
?>
Seems prety easy, but what if you want to generate it dinamically woops!!!. Imagine that you have a file with thousands of lines and each line is a purchase order from diferent clients:
<?php
/*function to add elements*/
function addArray(&$array, $id, $var)
{
  $tempArray = array( $var => $id);
  $array = array_merge ($array, $tempArray);
}
/*The same as above but the element is an array*/
function addArrayArr(&$array, $var, &$array1)
{
  $tempArray = array($var => $array1);
  $array = array_merge ($array, $tempArray);
}
/*labels of our array or heders of the file*/
$keyarr = array("customer","item");
/*info that may you read from a file line 1 and 2*/
$valarr0 = array("Client 1","Item a");
$valarr1 = array("Client 2","Item b");
$numofrows = 2;/*In our case is just two lines*/
$tmpArray = array();
for($i = 0; $i < $numofrows; $i++){
 $tmp = "valarr$i";
 $tmpvar = ${$tmp};/*Using var of vars tricky tricky*/
 foreach( $keyarr as $key=>$value){   
  addArray($tmparr,$tmpvar[$key],$value);
 }
 addArrayArr($finalarr,$i,$tmparr);
} /*voila all it's perfectly ordered on finalarr*/
/*Here we just print the info but you can insert it into a database*/
echo "Customer: ".$finalarr[0]["customer"]."<br>";
echo "Item: ".$finalarr[0]["item"]."<br>";
echo "Customer: ".$finalarr[1]["customer"]."<br>";
echo "Item: ".$finalarr[1]["item"]."<br>";     
?>
The lines above should print something like:
Customer: Client 1
Item: Item a
Customer: Client 2
Item: Item b
I hope someone find this useful.

Heres a simple yet intelligent way of setting an array, grabbing the values from the array using a loop.
<?php
$ary = array("1"=>'One','Two',"3"=>'Three');
$a = '0'; $b = count($ary);
while ($a <= $b) {
 $pr = $ary[$a];
 print "$pr<br>";
 $a++;
}
?>

Here are shorter versions of sam barrow's functions. From a PHP perspective these are O(1) (without getting into what's going on in the interpreter), instead of O(n).
<?php
function randomKey(array $array)
{
  return randomElement(array_keys($array));
}
function randomElement(array $array)
{
  if (count($array) === 0)
  {
    trigger_error('Array is empty.', E_USER_WARNING);
    return null;
  }
  $rand = mt_rand(0, count($array) - 1);
  $array_keys = array_keys($array);
  
  return $array[$array_keys[$rand]];
}
?>

The code bellow by dave@wp.pl:
$var_name='var';
$var=array(0,1,2,3,4);
echo $$var_name[2]; 
//prints NOTHING instead 2.
// prints 2 with PHP version 7.01 onwards
Note :
This results 2 with PHP version 7.01 onwards. Other versions throws a notice error

This is a useful way to get foreign key variables from a specific sql table.
This function can be used to include all relevant data from all relating tables:
<?php
function get_string_between($string, $start, $end){
     $string = " ".$string; 
     $ini = strpos($string,$start);
     if($ini == 0) 
        return $tbl; 
     $ini += strlen($start); 
     $len = strpos($string,$end,$ini) - $ini; 
     return substr($string,$ini,$len); 
} 
function get_foreign_keys($tbl) {
    $query = query_getrow("SHOW CREATE TABLE ".mysql_escape_string($tbl));
    $dat = explode('CONSTRAINT',$query[1]);
    foreach($dat as $d => $a) {
        if(strpos($a,"FOREIGN KEY"))
        $data['keys'][] = array($tbl,get_string_between($a,"` FOREIGN KEY (`","`) REFERENCES"));
    }            
    foreach($dat as $d => $a) {
        if(strpos($a,"REFERENCE"))
        $data['references'][] = explode('` (`',get_string_between($a,"REFERENCES `","`) ON"));
    }
    return $data;
}
//Example code:
    $data = get_foreign_keys('task_table');
    echo '<pre>';
    print_r($data);
    echo '</pre>';
?>
// $query[1] outputs:
CREATE TABLE `task_table` (
 `task_id` int(64) NOT NULL auto_increment,
 `ticket_id` int(64) NOT NULL,
 `task_type` varchar(64) NOT NULL,
 `comment` text,
 `assigned_to` int(11) default NULL,
 `dependant` int(64) default NULL,
 `resolved` int(1) default NULL,
 PRIMARY KEY (`task_id`),
 KEY `ticket_id` (`ticket_id`,`dependant`),
 KEY `assigned_to` (`assigned_to`),
 KEY `task_dependant` (`dependant`),
 CONSTRAINT `task_table_ibfk_1` FOREIGN KEY (`ticket_id`) REFERENCES `tickets_table` (`ticket_id`) ON DELETE CASCADE ON UPDATE CASCADE,
 CONSTRAINT `task_table_ibfk_2` FOREIGN KEY (`assigned_to`) REFERENCES `contact_table` (`contact_id`) ON DELETE CASCADE ON UPDATE CASCADE,
 CONSTRAINT `task_table_ibfk_3` FOREIGN KEY (`dependant`) REFERENCES `task_table` (`task_id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=latin1
// $data outputs:
Array (
  [keys] => Array
    (
      [0] => Array
        (
          [0] => task_table
          [1] => ticket_id
        )
      [1] => Array
        (
          [0] => task_table
          [1] => assigned_to
        )
      [2] => Array
        (
          [0] => task_table
          [1] => dependant
        )
    )
  [references] => Array
    (
      [0] => Array
        (
          [0] => tickets_table
          [1] => ticket_id
        )
      [1] => Array
        (
          [0] => contact_table
          [1] => contact_id
        )
      [2] => Array
        (
          [0] => task_table
          [1] => task_id
        )
    )
)

<?php
$foo = array('bar' => 'baz');
echo "Hello {$foo['bar']}!"; // Hello baz!
?> 
<?php
$firstquarter = array(1 => 'January', 'February', 'March');
print_r($firstquarter);
?> 
<?php
$fruits = array (
  "fruits" => array("a" => "orange", "b" => "banana", "c" => "apple"),
  "numbers" => array(1, 2, 3, 4, 5, 6),
  "holes" => array("first", 5 => "second", "third")
);
?>

During initialization php parses every value as expression. One can declare variables, do calculations, or even manipulate "current" array
<?php
$arr['A'] = [
  &$arr, // circular reference
  'key' => 'val',
  $arr['B'] = [ // declare array, insert key and then value
    'a' => 'b',
  ],
  ucfirst(strtolower('SOME TEXT')), 
  true ? 'TRUE' : 'FALSE', // evaluate expression
  $x = 3, // declare variable
  $x *= 3, // perform calculations
];
var_dump($arr);
// Output
/*
array(2) {
 'B' => array(1) {
  'a' => string(1) "b"
 }
 'A' => array(7) {
  [0] => array(2) {
   'B' => array(1) {
    ...
   }
   'A' => &array
  }
  'key' => string(3) "val"
  [1] => array(1) {
   'a' => string(1) "b"
  }
  [2] => string(9) "Some text"
  [3] => string(4) "TRUE"
  [4] => int(3)
  [5] => int(9)
 }
}
*/
?>

<?
    // This is a small script that shows how to use an multiple array
    for($x = 0;$x < 10;$x++){
        for($y = 0;$y < 10;$y++){
            $mat[$x][$y] = "$x,$y";
        }
    }
    for($x = 0;$x < count($mat);$x++){
        for($y = 0;$y < count($mat[$x]);$y++){
            echo  "mat[$x][$y]: " .
                $mat[$x][$y] . " ";
        }
        echo "\n";
    }
?>

The easiest way to "list" the values of either a normal 1 list array or a multi dimensional array is to use a foreach() clause.
Example for 1 dim array:
<?php
  $arr = array( 1, 2, 3, 4, 5 );
  foreach ( $arr as $val ) { 
    echo "Value: $Val\n";
   }
?>
For multi dim array:
<?php
   $arr = array( 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four, 5 => 'five');
   foreach ( $arr as $key => $value ) { 
    echo "Key: $key, Value: $value\n";
   }
?>
This is quite possibly the easiest way i've found to iterate through an array.

Multidimensional arrays are actually single-dimensional arrays nested inside other single-dimensional arrays.
$array[0] refers to element 0 of $array
$array[0][2] refers to element 2 of element 0 of $array.
If an array was initialized like this:
$array[0] = "foo";
$array[1][0] = "bar";
$array[1][1] = "baz";
$array[1][2] = "bam";
then:
is_array($array) = TRUE
is_array($array[0]) = FALSE
is_array($array[1]) = TRUE
count($array) = 2 (elements 0 and 1)
count($array[1] = 3 (elements 0 thru 2)
This can be really useful if you want to return a list of arrays that were stored in a file or something:
$array[0] = unserialize($somedata);
$array[1] = unserialize($someotherdata);
if $somedata["foo"] = 42 before it was serialized previously, you'd now have this:
$array[0]["foo"] = 42

If you are creating an array with a large number of static items, you will find serious performance differences between using the array() function and the $array[] construct. For example:
<?
 // Slower method
 $my_array = array(1, 2, 3,500);
 
 // Faster method
 $my_array[] = 1;
 $my_array[] = 2;
 $my_array[] = 3;
 $my_array[] = 500;
?>

here is the sort of "textbook" way to output the contents of an array which avoids using foreach() and allows you to index & iterate through the array as you see fit:
<?php
$arrayName = array("apples", "bananas", "oranges", "pears");
$arrayLength = count($arrayName);
for ($i = 0; $i < $arrayLength; $i++){
  echo "arrayName at[" . $i . "] is: [" .$arrayName[$i] . "]<br>\n";
}
?>
enjoy!
-tim

When using an array to create a list of keys and values for a select box generator which will consist of states I found using "NULL" as an index and ""(empty value) as a value to be useful:
<?php
$states = array(
  0  => 'Select a State',
  NULL => '',
  1  => 'AL - Alabama',
  2  => 'AK - Alaska',
  # And so on ...
);
$select = '<select name="state" id="state" size="1">'."\r\n";
foreach($states as $key => $value){
  $select .= "\t".'<option value="'.$key.'">' . $value.'</option>'."\r\n";
}
$select .= '</select>';
echo $select;
?>
 This will print out:
<select name="state" id="state" size="1">
  <option value="0">Select a State</option>
  <option value=""></option>
  <option value="1">AL - Alabama</option>
  <option value="2">AK - Alaska</option>
  # And so on ...
</select>
Now a user has a blank value to select if they later decide to not provide their address in the form. The first two options will return TRUE when checked against the php function - EMPTY() after the form is submitted when processing the form

This function converts chunks of a string in an array:
function array_str($str, $len) {
 $newstr = '';
 for($i = 0; $i < strlen($str); $i++) {
  $newstr .= substr($str, $i, $len);
 }
 return $newstr;
}
use it as:
$str = "abcdefghilmn";
echo "<table width=\"100%\">\n";
foreach(array_str($str, 4) as $chunk) {
 echo "<tr><td>".$chunk."</td></tr>\n";
}
echo "</table>";
this prints:
------
abcd
------
efgh
------
ilmn
------
It don't use regular expressions. Please add this function to php :)

How to use array() to create an array of references rather than of copies? (Especially needed when dealing with objects.) I played around somewhat and found a solution: place & before the parameters of array() that shall be references. My PHP version is 4.3.10.
Demonstration:
<?php
$ref1 = 'unchanged';
$ref2 = & $ref1;
$array_of_copies = array($ref1, $ref2);
print_r($array_of_copies); // prints: Array ( [0] => unchanged [1] => unchanged ) 
$array_of_copies[0] = 'changed'; // $ref1 = 'changed'; is not equivalent, as it was _copied_ to the array
print_r($array_of_copies); // prints: Array ( [0] => changed [1] => unchanged ) 
$array_of_refs = array(& $ref1, & $ref2); // the difference: place & before arguments
print_r($array_of_refs); // prints: Array ( [0] => unchanged [1] => unchanged ) 
$array_of_refs[0] = 'changed'; // $ref1 = 'changed'; is equivalent as $array_of_refs[0] references $ref1
print_r($array_of_refs, true); // prints: Array ( [0] => changed [1] => changed ) 
?>

Be careful if you need to use mixed types with a key of 0 in an array, as several distinct forms end up being the same key:
$a = array();
$a[null] = 1;
$a[0] = 2;
$a['0'] = 3;
$a["0"] = 4;
$a[false] = 5;
$a[0.0] = 6;
$a[''] = 7;
$a[] = 8;
print_r( $a );
This will print out only 3 values: 6, 7, 8.

If you want to create an array of a set size and you have PHP4, use
array_pad(array(), $SIZE, $INITIAL_VALUE); This can be handy if you wish
to initialize a bunch of variables at once: 
list($Var1, $Var2, etc) = array_pad(array(), $NUMBER_OF_VARS,
$INITIAL_VALUE);
Jay Walker
Las Vegas Hotel Associate
http://www.ezlasvegas.net

Some tricky functions;
<?php
function is_array_assoc($arr) {
  if (is_array($arr)) {
    foreach ($arr as $k => $v) {
      if (is_string($k) || (is_int($k) && $k < 0)) {
        return 1;
      }
    }
    return 0;
  }
  return -1;
}
function is_array_multi($arr) {
  return is_array($arr)
    ? (count($arr) != count($arr, COUNT_RECURSIVE) ? 1 : 0)
    : -1;
}
$arr[] = array("foo", "bar", 1.09);
$arr[] = array("red", "yellow", 1 => "foo");
$arr[] = array("red", "yellow", -1 => "foo");
$arr[] = array("x" => array("red", "yellow"), "y" => array("one", "two"));
$arr[] = array();
$arr[] = "s";
foreach ($arr as $a) {
  echo is_array_assoc($a) ."\n";
}
echo "\n";
foreach ($arr as $a) {
  echo is_array_multi($a) ."\n";
}
?>
0
0
1
1
0
-1
0
0
0
1
0
-1
<?php
function array_count($arr) {
  $r = 0;
  foreach ($arr as $k => $v) {
    if (is_array($v)) {
      $r++;
    }
  }
  return $r;
}
function array_count_all($arr, $r = 0) {
  foreach ($arr as $k => $v) {
    if (is_array($v)) {
      $r = array_count_all($v, $r);
      $r++;
    }
  }
  return $r;
}
$a = array("foo", "bar", 1.09, array(1,2,3), array("a" => "aaa"));
echo array_count($a); // 2
$a = array(
  "foo", "bar", 1.09, 
  "x" => array(1,2,3), 
  array("a" => "aaa", "b" => array(), "c" => array(""), "d" => array("")), 
  "e" => array(""), 
  "z" => array(""), 
  "q" => array("", array()),
  "w" => array("lorem", 1 => "impsum", 18, "dolor", array("last as 11th array"))
);
echo array_count_all($a); // 11
?>

Similarly to a comment by stlawson at sbcglobal dot net on this page:
http://www.php.net/basic-syntax.instruction-separation
It is usually advisable to define your arrays like this:
$array = array(
   'foo',
   'bar',
);
Note the comma after the last element - this is perfectly legal. Moreover,
it's best to add that last comma so that when you add new elements to the
array, you don't have to worry about adding a comma after what used to be
the last element.
<?php
$array = array(
   'foo',
   'bar',
   'baz',
);
?>

I wanted to be able to control the flow of data in a loop instead of just building tables with it or having to write 500 select statements for single line items. This is what I came up with thanks to the help of my PHP brother in FL. Hope someone else gets some use out it. 
<?
//set array variable 
$results = array();
//talk to the db
$query = "SELECT * FROM yourtable";
$result = mysql_query($query) or die(mysql_error());
//count the rows and fields
$totalRows = mysql_num_rows($result);
$totalFields = mysql_num_fields($result);
//start the loop
for ( $i = 0; $i < $totalRows; ++$i ) {
//make it 2 dim in case you change your order
 $results[$i] = mysql_fetch_array($result); 
//call data at will controlling the loop with the array
echo $results[your_row_id]['your_field_name']; }
//print the entire array to see what lives where
print_r($results); ?>

In PHP 4.2.3 (and maybe earlier versions) arrays with numeric indexes may be initialized to start at a specific index and then automatically increment the index. This will save you having to write the index in front of every element for arrays that are not zero-based. 
The code:
<?php
         $a = array
    (
      21  => 1,
      2,
      3,
    );
  print '<pre>';
  print_r($a);
  print '</pre>';
?>
will print:
<?php
Array
(
  [21] => 1
  [22] => 2
  [23] => 3
)
?>

Consider:
file inc1.php
-------------
<?php
return 'key';
file inc2.php
-------------
<?php
return 'value';
Test:
<?php
$a = [
  include 'inc1.php' => include 'inc2.php'
];
var_dump($a);
/* It works!!!
array(1) {
 'key' =>
 string(5) "value"
}
*/

The code bellow:
$var_name='var';
$var=array(0,1,2,3,4);
echo $$var_name[2]; 
prints NOTHING instead 2.

i tried to find a way to create BIG multidimensional-arrays. but the notes below only show the usage of it, or the creation of small arrays like $matrix=array('birne', 'apfel', 'beere');
for an online game, i use a big array (50x80) elements.
it's no fun, to write the declaration of it in the ordinary way.
here's my solution, to create an 2d-array, filled for example with raising numbers.
<?php
$matrix=array();
$sx=30;
$sy=40;
$i=1;
for ($y=0; $y<$sy; $y++)
{
  array_push($matrix,array());
  for ($x=0; $x<$sx; $x++)
  {
    array_push($matrix[$y],array());
    $matrix[$x][$y]=$i;
    $i++;
  }
}
?>
if there is a better way, plz send an email. i always want to learn more php!

Easy function to unarray an array :-)
It will make $array['something'] => $something.
Usefull for making code more clear.
example of use:
<?
function unarray($row) {
  foreach($row as $key => $value) {
    global $$key;
    $$key = $value;
  }
}
$sql = mysql_query("SELECT * FROM `pracownicy`");
while ($row = mysql_fetch_assoc($sql)) {
  unarray($row);
  echo $idpracownika.'<br>'; //instead of $row['idpracownika']
}
?>

Here's a cool tip for working with associative arrays- 
Here's what I was trying to accomplish: 
I wanted to hit a DB, and load the results into an associative array, since I only had key/value pairs returned. I loaded them into an array, because I wanted to manipulate the data further after the DB select, but I didn't want to hit the DB more than necessary. 
Here's how I did it: 
<?php
//assume db connectivity
//load it all into the associative array
$sql = "SELECT key,value FROM table";
$result = mysql_query($sql);
while($row = mysql_fetch_row($result)) {
$myArray[$row[0]] = $row[1];
}
//now we expand it
while(list($key,$value) = each($myArray)) {
echo "$key : $value";
} 
?>
I found this to be super efficient, and extremely cool.

Be careful not to create an array on top of an already existing variable:
<?php
$name = "John";
$name['last'] = "Doe"; 
?>
$name becomes "Dohn" since 'last' evaluates to the 0th position of $name.
Same is true for multi-arrays.

This helper function creates a multi-dimensional array. For example, creating a three dimensional array measuring 10x20x30: <?php $my_array = multi_dim(10, 20, 30); ?>
<?php
function multi_dim()
{  
  $fill_value = null;
  
  for ($arg_index = func_num_args() - 1; $arg_index >= 0; $arg_index--) {
    $dim_size = func_get_arg($arg_index);
    $fill_value = array_fill(0, $dim_size, $fill_value);
  }
  
  return $fill_value;
}
?>

Recursive function similar to print_r for describing anidated arrays in html <ol>. Maybe it's useful for someone.
<?php
function describeAnidatedArray($array)
{
  $buf = '';
  foreach($array as $key => $value)
  {
    if(is_array($value))
    {
      $buf .= '<ol>' . describeAnidatedArray($value) . '</ol>';
    }
    else
      $buf .= "<li>$value</li>";
  }
  return $buf;
}
// Example: 
$array = array("a", "b", "c", array("1", "2", array("A", "B")), array("3", "4"), "d");
echo describeAnidatedArray($array);
?>
output:
# a
# b
# c
  1. 1
  2. 2
     1. A
     2. B
  1. 3
  2. 4
# d