Last updated: Sat, 17 Jul 2004

Arrays

An array in PHP is actually an ordered map. A map is a type that maps values to keys. This type is optimized in several ways, so you can use it as a real array, or a list (vector), hashtable (which is an implementation of a map), dictionary, collection, stack, queue and probably more. Because you can have another PHP array as a value, you can also quite easily simulate trees.

Explanation of those data structures is beyond the scope of this manual, but you'll find at least one example for each of them. For more information we refer you to external literature about this broad topic.

Syntax

Specifying with array()

An array can be created by the array() language-construct. It takes a certain number of comma-separated key => value pairs.

array( [key =>] value
     , ...
     )
// key may be an integer or string
// value may be any value


<?php

$arr = array("foo" => "bar", 12 => true);



echo $arr["foo"]; // bar

echo $arr[12];    // 1

?>

A key may be either an integer or a string. If a key is the standard representation of an integer, it will be interpreted as such (i.e. "8" will be interpreted as 8, while "08" will be interpreted as "08"). There are no different indexed and associative array types in PHP; there is only one array type, which can both contain integer and string indices.

A value can be of any PHP type.


<?php

$arr = array("somearray" => array(6 => 5, 13 => 9, "a" => 42));



echo $arr["somearray"][6];    // 5

echo $arr["somearray"][13];   // 9

echo $arr["somearray"]["a"];  // 42

?>

If you do not specify a key for a given value, then the maximum of the integer indices is taken, and the new key will be that maximum value + 1. If you specify a key that already has a value assigned to it, that value will be overwritten.


<?php

// This array is the same as ...

array(5 => 43, 32, 56, "b" => 12);



// ...this array

array(5 => 43, 6 => 32, 7 => 56, "b" => 12);

?>

Uyar�

As of PHP 4.3.0, the index generation behaviour described above has changed. Now, if you append to an array in which the current maximum key is negative, then the next key created will be zero (0). Before, the new index would have been set to the largest existing key + 1, the same as positive indices are.

Using TRUE as a key will evaluate to integer 1 as key. Using FALSE as a key will evaluate to integer 0 as key. Using NULL as a key will evaluate to the empty string. Using the empty string as key will create (or overwrite) a key with the empty string and its value; it is not the same as using empty brackets.

You cannot use arrays or objects as keys. Doing so will result in a warning: Illegal offset type.

Creating/modifying with square-bracket syntax

You can also modify an existing array by explicitly setting values in it.

This is done by assigning values to the array while specifying the key in brackets. You can also omit the key, add an empty pair of brackets ("[]") to the variable name in that case.

$arr[key] = value;
$arr[] = value;
// key may be an integer or string
// value may be any value

If $arr doesn't exist yet, it will be created. So this is also an alternative way to specify an array. To change a certain value, just assign a new value to an element specified with its key. If you want to remove a key/value pair, you need to unset() it.


<?php

$arr = array(5 => 1, 12 => 2);



$arr[] = 56;    // This is the same as $arr[13] = 56;

                // at this point of the script



$arr["x"] = 42; // This adds a new element to

                // the array with key "x"

                

unset($arr[5]); // This removes the element from the array



unset($arr);    // This deletes the whole array

?>

Not: As mentioned above, if you provide the brackets with no key specified, then the maximum of the existing integer indices is taken, and the new key will be that maximum value + 1 . If no integer indices exist yet, the key will be 0 (zero). If you specify a key that already has a value assigned to it, that value will be overwritten.

Uyar�
As of PHP 4.3.0, the index generation behaviour described above has changed. Now, if you append to an array in which the current maximum key is negative, then the next key created will be zero (0). Before, the new index would have been set to the largest existing key + 1, the same as positive indices are.

Note that the maximum integer key used for this need not currently exist in the array. It simply must have existed in the array at some time since the last time the array was re-indexed. The following example illustrates:
<?php // Create a simple array. $array = array(1, 2, 3, 4, 5); print_r($array); // Now delete every item, but leave the array itself intact: foreach ($array as $i => $value) { unset($array[$i]); } print_r($array); // Append an item (note that the new key is 5, instead of 0 as you // might expect). $array[] = 6; print_r($array); // Re-index: $array = array_values($array); $array[] = 7; print_r($array); ?>
The above example would produce the following output:
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)
Array
(
)
Array
(
    [5] => 6
)
Array
(
    [0] => 6
    [1] => 7
)

Useful functions

There are quite a few useful functions for working with arrays. See the array functions section.

Not: The unset() function allows unsetting keys of an array. Be aware that the array will NOT be reindexed. If you only use "usual integer indices" (starting from zero, increasing by one), you can achieve the reindex effect by using array_values().

<?php $a = array(1 => 'one', 2 => 'two', 3 => 'three'); unset($a[2]); /* will produce an array that would have been defined as $a = array(1 => 'one', 3 => 'three'); and NOT $a = array(1 => 'one', 2 =>'three'); */ $b = array_values($a); // Now $b is array(0 => 'one', 1 =>'three') ?>

The foreach control structure exists specifically for arrays. It provides an easy way to traverse an array.

Array do's and don'ts

Why is `$foo[bar]` wrong?

You should always use quotes around a string literal array index. For example, use $foo['bar'] and not $foo[bar]. But why is $foo[bar] wrong? You might have seen the following syntax in old scripts:


<?php

$foo[bar] = 'enemy';

echo $foo[bar];

// etc

?>

This is wrong, but it works. Then, why is it wrong? The reason is that this code has an undefined constant (bar) rather than a string ('bar' - notice the quotes), and PHP may in future define constants which, unfortunately for your code, have the same name. It works because PHP automatically converts a bare string (an unquoted string which does not correspond to any known symbol) into a string which contains the bare string. For instance, if there is no defined constant named bar, then PHP will substitute in the string 'bar' and use that.

Not: This does not mean to always quote the key. You do not want to quote keys which are constants or variables, as this will prevent PHP from interpreting them.

<?php error_reporting(E_ALL); ini_set('display_errors', true); ini_set('html_errors', false); // Simple array: $array = array(1, 2); $count = count($array); for ($i = 0; $i < $count; $i++) { echo "\nChecking $i: \n"; echo "Bad: " . $array['$i'] . "\n"; echo "Good: " . $array[$i] . "\n"; echo "Bad: {$array['$i']}\n"; echo "Good: {$array[$i]}\n"; } ?>
Not: The output from the above is:
Checking 0: 
Notice: Undefined index:  $i in /path/to/script.html on line 9
Bad: 
Good: 1
Notice: Undefined index:  $i in /path/to/script.html on line 11
Bad: 
Good: 1

Checking 1: 
Notice: Undefined index:  $i in /path/to/script.html on line 9
Bad: 
Good: 2
Notice: Undefined index:  $i in /path/to/script.html on line 11
Bad: 
Good: 2

More examples to demonstrate this fact:


<?php

// Let's show all errors

error_reporting(E_ALL);



$arr = array('fruit' => 'apple', 'veggie' => 'carrot');



// Correct

print $arr['fruit'];  // apple

print $arr['veggie']; // carrot



// Incorrect.  This works but also throws a PHP error of

// level E_NOTICE because of an undefined constant named fruit

// 

// Notice: Use of undefined constant fruit - assumed 'fruit' in...

print $arr[fruit];    // apple



// Let's define a constant to demonstrate what's going on.  We

// will assign value 'veggie' to a constant named fruit.

define('fruit', 'veggie');



// Notice the difference now

print $arr['fruit'];  // apple

print $arr[fruit];    // carrot



// The following is okay as it's inside a string.  Constants are not

// looked for within strings so no E_NOTICE error here

print "Hello $arr[fruit]";      // Hello apple



// With one exception, braces surrounding arrays within strings

// allows constants to be looked for

print "Hello {$arr[fruit]}";    // Hello carrot

print "Hello {$arr['fruit']}";  // Hello apple



// This will not work, results in a parse error such as:

// Parse error: parse error, expecting T_STRING' or T_VARIABLE' or T_NUM_STRING'

// This of course applies to using autoglobals in strings as well

print "Hello $arr['fruit']";

print "Hello $_GET['foo']";



// Concatenation is another option

print "Hello " . $arr['fruit']; // Hello apple

?>

When you turn error_reporting() up to show E_NOTICE level errors (such as setting it to E_ALL) then you will see these errors. By default, error_reporting is turned down to not show them.

As stated in the syntax section, there must be an expression between the square brackets ('[' and ']'). That means that you can write things like this:


<?php

echo $arr[somefunc($bar)];

?>

This is an example of using a function return value as the array index. PHP also knows about constants, as you may have seen the E_* ones before.


<?php

$error_descriptions[E_ERROR]   = "A fatal error has occured";

$error_descriptions[E_WARNING] = "PHP issued a warning";

$error_descriptions[E_NOTICE]  = "This is just an informal notice";

?>

Note that E_ERROR is also a valid identifier, just like bar in the first example. But the last example is in fact the same as writing:


<?php

$error_descriptions[1] = "A fatal error has occured";

$error_descriptions[2] = "PHP issued a warning";

$error_descriptions[8] = "This is just an informal notice";

?>

because E_ERROR equals 1, etc.

As we already explained in the above examples, $foo[bar] still works but is wrong. It works, because bar is due to its syntax expected to be a constant expression. However, in this case no constant with the name bar exists. PHP now assumes that you meant bar literally, as the string "bar", but that you forgot to write the quotes.

So why is it bad then?

At some point in the future, the PHP team might want to add another constant or keyword, or you may introduce another constant into your application, and then you get in trouble. For example, you already cannot use the words empty and default this way, since they are special reserved keywords.

Not: To reiterate, inside a double-quoted string, it's valid to not surround array indexes with quotes so "$foo[bar]" is valid. See the above examples for details on why as well as the section on variable parsing in strings.

Converting to array

For any of the types: integer, float, string, boolean and resource, if you convert a value to an array, you get an array with one element (with index 0), which is the scalar value you started with.

If you convert an object to an array, you get the properties (member variables) of that object as the array's elements. The keys are the member variable names.

If you convert a NULL value to an array, you get an empty array.

Comparing

It is possible to compare arrays by array_diff() and by Array operators.

Examples

The array type in PHP is very versatile, so here will be some examples to show you the full power of arrays.


<?php

// this

$a = array( 'color' => 'red',

            'taste' => 'sweet',

            'shape' => 'round',

            'name'  => 'apple',

                       4        // key will be 0

          );



// is completely equivalent with

$a['color'] = 'red';

$a['taste'] = 'sweet';

$a['shape'] = 'round';

$a['name']  = 'apple';

$a[]        = 4;        // key will be 0



$b[] = 'a';

$b[] = 'b';

$b[] = 'c';

// will result in the array array(0 => 'a' , 1 => 'b' , 2 => 'c'),

// or simply array('a', 'b', 'c')

?>

�rnek 6-4. Using array()


<?php

// Array as (property-)map

$map = array( 'version'    => 4,

              'OS'         => 'Linux',

              'lang'       => 'english',

              'short_tags' => true

            );

            

// strictly numerical keys

$array = array( 7,

                8,

                0,

                156,

                -10

              );

// this is the same as array(0 => 7, 1 => 8, ...)



$switching = array(         10, // key = 0

                    5    =>  6,

                    3    =>  7, 

                    'a'  =>  4,

                            11, // key = 6 (maximum of integer-indices was 5)

                    '8'  =>  2, // key = 8 (integer!)

                    '02' => 77, // key = '02'

                    0    => 12  // the value 10 will be overwritten by 12

                  );

                  

// empty array

$empty = array();         

?>

�rnek 6-5. Collection


<?php

$colors = array('red', 'blue', 'green', 'yellow');



foreach ($colors as $color) {

    echo "Do you like $color?\n";

}



?>

This will output:

Do you like red?
Do you like blue?
Do you like green?
Do you like yellow?

Note that it is currently not possible to change the values of the array directly in such a loop. A workaround is the following:

�rnek 6-6. Collection


<?php

foreach ($colors as $key => $color) {

    // won't work:

    //$color = strtoupper($color);

    

    // works:

    $colors[$key] = strtoupper($color);

}

print_r($colors);

?>

This will output:

Array
(
    [0] => RED
    [1] => BLUE
    [2] => GREEN
    [3] => YELLOW
)

This example creates a one-based array.

�rnek 6-7. One-based index


<?php

$firstquarter  = array(1 => 'January', 'February', 'March');

print_r($firstquarter);

?>

This will output:

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

�rnek 6-8. Filling an array


<?php

// fill an array with all items from a directory

$handle = opendir('.');

while (false !== ($file = readdir($handle))) {

    $files[] = $file;

}

closedir($handle); 

?>

Arrays are ordered. You can also change the order using various sorting functions. See the array functions section for more information. You can count the number of items in an array using the count() function.

�rnek 6-9. Sorting an array


<?php

sort($files);

print_r($files);

?>

Because the value of an array can be anything, it can also be another array. This way you can make recursive and multi-dimensional arrays.

�rnek 6-10. Recursive and multi-dimensional arrays


<?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"

                                     )

                );



// Some examples to address values in the array above 

echo $fruits["holes"][5];    // prints "second"

echo $fruits["fruits"]["a"]; // prints "orange"

unset($fruits["holes"][0]);  // remove "first"



// Create a new multi-dimensional array

$juices["apple"]["green"] = "good"; 

?>

You should be aware that array assignment always involves value copying. You need to use the reference operator to copy an array by reference.


<?php

$arr1 = array(2, 3);

$arr2 = $arr1;

$arr2[] = 4; // $arr2 is changed,

             // $arr1 is still array(2, 3)

             

$arr3 = &$arr1;

$arr3[] = 4; // now $arr1 and $arr3 are the same

?>

Objects

Strings

Last updated: Sat, 17 Jul 2004

add a note User Contributed Notes
Arrays

hek at theeks dot net
24-Oct-2008 08:58


Note that NULL is not exactly a scalar value, so the following two lines of code do NOT produce identical arrays.





<?php


$x = (array) null; // $x ends up an empty array (zero elements)


$y = array(null); // $y ends up an array containing one element (a null)


?>

pinkgothic at gmail dot com
13-Sep-2008 08:49


Re: fmouse,



the phenomenom you're describing pertains to superglobals, not arrays, and it only applies in a very specific scope. Check out http://de.php.net/manual/en/language.variables.variable.php :



"Please note that variable variables cannot be used with PHP's Superglobal arrays within functions or class methods. The variable $this is also a special variable that cannot be referenced dynamically."

frywater
04-Jun-2008 04:43


>fmouse



Variable variables can be used with arrays as discussed in the variable variable section.

Also, from your code, $somevar can be an array and still work fine.



$fum = "somevar";

$$fum = array(); // $somevar is now an array

$foo = $$fum;

print_r( $foo); // we get an empty array printed 



print_r() doesn't just print arrays, it prints any variable type.

If you pass it a variable, that hasn't been defined yet, it won't know how to print it.



You would get this same results by passing any undefined variable such as:

print_r( $bar );  // PHP Notice: undefined variable ...$bar

fmouse at fmp dot com
29-Apr-2008 01:14


Using variables as array names no longer works in PHP5.



$fum = "somevar";

$foo = $$fum;



# Still works if $somevar isn't an array.  $foo contains the value of $somevar



but ....



$fum = "_POST";

print_r($$fum);

print_r(${$fum});



Neither form of indirection works in this context.  $$fum comes back empty.



If you have PHP4 code that used this kind of indirection you can work around the change in PHP5 using an eval().



$fum = "_POST";

$foo = eval("return $$fum;");

print_r($foo);



This works!

rama dot devi at gmail dot com
18-Mar-2008 02:52


Sorting double dimensional arrays by a specified key bothe for Strings and for integers: 

Ex:

 

 $personDetails =  array( array("firstName" => "Nancy", "lastName" => "Grace", "age" => 22), array("firstName" => "Andy",  "lastName" => "Peter", "age" => 28),                           array("firstName" => "Jim",   "lastName" => "Gary",  "age" => 25), array("firstName" => "Lary",  "lastName" => "James", "age" => 28),  array("firstName" => "Peter", "lastName" => "David", "age" => 17), array("firstName" => "Raj",   "lastName" => "King",  "age" => 9),                           array("firstName" => "John",  "lastName" => "Baxter","age" => 35) );

//To sort the array by firstName:-

     function sortFirstName($p1, $p2) {

          return strnatcmp($p1['firstName'], $p2['firstName']);

      }

      usort($personDetails, 'sortFirstName');



//To sort by an integer Field



   function sortByInteger(&$personDetails, $field) {

      $sort = "return strnatcmp(\$p1['$field'], \$p2['$field']);";

       usort($personDetails, create_function('$p1,$p2', $sort));

        return $personDetails;

    }



    $personDetails = sortByInteger($personDetails, 'age');

//To sort the array in Descending order by a key, It can be done by adding "-" sign before strnatcmp() function.



I hope this helps

ken underscore yap atsign email dot com
09-Jan-2008 08:00


"If you convert a NULL value to an array, you get an empty array."



This turns out to be a useful property. Say you have a search function that returns an array of values on success or NULL if nothing found.



$values = search(...);



Now you want to merge the array with another array. What do we do if $values is NULL? No problem:



$combined = array_merge((array)$values, $other);



Voila.

pepesantillan at gmail dot com
18-Dec-2007 04:25


z on 22-Apr-2005 12:10 wrote:

-----------------------------------------------

Here's a simple function to insert a value into some position in an array



<?php

function array_insert($array,$pos,$val)

{

    $array2 = array_splice($array,$pos);

    $array[] = $val;

    $array = array_merge($array,$array2);

   

    return $array;

}

?>



and now for example...

<?php

$a = array("John","Paul","Peter");

$a = array_insert($a,1,"Mike");

?>



Now $a will be "John","Mike","Paul","Peter"

-----------------------------------------------



Im learning to use PHP and reading about array_splice found that



<?php

function array_insert($array,$pos,$val)

{

    $array2 = array_splice($array,$pos);

    $array[] = $val;

    $array = array_merge($array,$array2);



    return $array;

}



$a = array("John","Paul","Peter");

$a = array_insert($a,1,"Mike");

print_r($a);

?>



would output the same as



<?php

$b = array("John","Paul","Peter");

array_splice($b,1,0,array("Mike"));

print_r($b);

?>

SID TRIVEDI
10-Oct-2007 02:14


<?php



//Simple Login Script using associative array.



//You may modify the codes and use $_POST['FORM_FIELD_DATA'] for your web-page.

//You may spice-up the codes with more form field validation & security features.



//$user_name=$_POST['user_name'];

//$password=$_POST['password'];



$test_user_name = 'michelle_smith'; //for testing purpose only

$test_password = 'msmith321';        //for testing purpose only

$user_name = $test_user_name;

$password = $test_password;



// here user_name is key and password is the value of an array..

// website owner has to add new user/site member manually in $login_array



$login_array = array(

                'user_name' => 'password',

                'alex_duff' => 'alx321', 

                    'xena78' => 'xena321',

                'dela_pena' => 'delp321',

                'shawn_1981' => 'shw81',

                'michelle_smith' => 'msmith321');



ksort ($login_array);

reset($login_array);

if (isset($login_array[$user_name]))

{

$pass_check = $login_array[$user_name];

if ($password === $pass_check)

{

echo  "Welcome, $user_name!\n<br>"; //may redirect to specific webpage.

}

else

{

echo "Please try again!"; //may redirect to Error page.

}

}

else

{

    echo "Please register with us. Thanks!"; //may redirect to registration page.

    exit();

    

}

echo("\n<br>");

echo 'Thanks to Thies C. Arntzen, Stig Bakken, Shane Caraveo, Andi Gutmans, Rasmus Lerdorf, Sam Ruby, Sascha Schumann, Zeev Suraski, Jim Winstead, Andrei Zmievski for wonderful PHP!';



?>

carl at linkleaf dot com
06-Sep-2007 11:36


Its worth noting that there does not appear to be any functional limitations on the length or content of string indexes. The string indexes for your arrays can contain any characters, including new line characters, and can be of any length:



<?php



$key = "XXXXX";

$test = array($key => "test5");



for ($x = 0; $x < 500; $x++) {

  $key .= "X";

  $value = "test" . strlen($key);

  $test[$key] = $value;

}



echo "<pre>";

print_r($test);

echo "</pre>";



?>



Keep in mind that using extremely long array indexes is not a good practice and could cost you lots of extra CPU time. However, if you have to use a long string as an array index you won't have to worry about the length or content.

Gautam
30-Aug-2007 01:56


<?php

//EXAMPLE  of Multi-Dimentional Array where as an array's keys are an array itself.

//It's so easy to create one like this.



$movie_to_watch = array ('Action'=>

          array('Kanu Reeves' => 'Matrix Reloaded',

                      'Pearce Brosnan' => 'Die Another Day',

                      'Tom Cruz' => 'Mission Impossible',

                      'Jason Statham' => 'Crank',

                      'Danzel Washington' => 'Man on Fire'),

                'Comedy' =>

                array ('Charlie Chaplin' => 'City Lights',

                       'Jim Carrey'    => 'Cable Guy',

                       'Rowan Atkinson' => 'The Ultimate Disaster'));

$type_wanted = 'Action'; //You may switch type from Action to Comedy.

$hero_wanted = 'Pearce Brosnan'; // You may switch hero from Pearce Brosnan to Jim Carrey.



print ("$hero_wanted 's  $type_wanted movie is " . $movie_to_watch[$type_wanted][$hero_wanted].".");

// produces browser output as under:

// Pearce Brosnan 's Action movie is Die Another Day.

?>

Olegk, getmequick[at]gmail[dot]com
21-Aug-2007 02:59


Hey..



here is a function which helps to avoid using empty/isset

checkings for arrays.



(it's acts simillar to 'default' modifier in Smarty)



Using this function you will avoid 'Undefined index' or 

'Undefined offset' error.



<?php



$_POST['id']['other'] = 'val1';



/*

key exist (same as $_POST['id'][other])

*/

echo getRequestParam('id[other]', 'default value');



/*

key doesn't exist, we get default value (same as $_POST['var'])

*/



echo getRequestParam('var', 'default value');



function getRequestParam( $var, $default = '', $method = 'post' )

{

    preg_match_all('!(\w+)!i',$var, $match );

    array_shift($match);

    $_vars = $match[0];

    $ret = null;    

    

    if(     strtoupper($method)   ==  'POST' ) {

        $ret = _findRequestParam($_vars, $_POST);

    }

    elseif( strtoupper($method) == 'GET' ) {

        $ret = _findRequestParam($_vars, $_GET);

    }

    elseif( strtoupper($method) == 'COOKIE' ) {

        $ret = _findRequestParam($_vars, $_COOKIE);

    

    }

    elseif( strtoupper($method) == 'SESSION' ) {

        $ret = _findRequestParam($_vars, $_SESSION);

    }    

    

    if (! $ret ) 

          return $default;

    else 

        return $ret;        

    

}



/**

@access private

*/



function _findRequestParam($vars, $find_in , $curr_key = 0)

{

    static $ret;

    

    if( array_key_exists($vars[$curr_key], $find_in) ) {

        if( count( $vars)-1 == $curr_key ) {

            $ret =  $find_in[$vars[$curr_key]];

        }

        elseif( $curr_key < count( $vars)-1 ) {

            _findRequestParam( $vars, $find_in[$vars[$curr_key]], $curr_key+1  );        

        }    

    }



    return $ret;



}



?>



Hope this will help someone!

conorj
14-Jul-2007 08:34


Another note on unquoted array indices. Because it is first interpreted as a constant, it must obey the naming convention of constants. i.e. a letter or underscore followed by optional letter, digit and/or underscore characters.



Therefore while the following array declaration is legal:

$a = array('1st'=>'First','2nd'=>'Second');



Trying to access either array item as follows causes an error:



$first = "$a[1st]";

$second = "$a[2nd]";

moehbass at gmail dot com
10-Jul-2007 05:41


<b>Mark Gukov</b> wrote below:



Regarding the fact that there's no need to quote arrays keys when enclosed in double quotes: it only applies to single dimensional arrays.



The following works fine:



<?php

$r['a'] = 'apple';

echo "$r[a] is tasty.";

?>



...but in the case of multi-dimensional arrays:



<?php

$r['a']['b'] = 'banana';

echo "$r[a][b] is tasty.";

?>



would result in "Array[c] is tasty."

-----------------------------------------------------------------



However, the following runs fine;

$r['a']['b'] = 'banana';

echo "{$r[a][b]} is tasty.";



Just box it!

don dot hosek at gmail dot com
23-May-2007 05:37


It's slightly faster to use array_splice to remove an element of an array:

array_splice($array, $index, 1)

than to do it using the suggested method of unset and reindex:

unset($array[$index]);

$array = array_values($array);



The difference, however, is very small. With 950 iterations I had times of 

unset and reindex: 0.22837495803833

splice: 0.22392416000366

lesantoso at yahoo dot com
20-Mar-2007 03:14


This Indonesian number speller function is twice

faster(*) than the one provided in class Terbilang by

anghuda(at)gmail(dot)com (25-May-2006 08:52):



http://www.lesantoso.com/terbilang.html



(*) 2.1 vs. 4.2 seconds in processing 10000 random numbers

Spudley
16-Mar-2007 02:44


On array recursion...



Given the following code:



<?

$myarray = array('test',123);

$myarray[] = &$myarray;

print_r($myarray);

?>



The print_r() will display *RECURSION* when it gets to the third element of the array.



There doesn't appear to be any other way to scan an array for recursive references, so if you need to check for them, you'll have to use print_r() with its second parameter to capture the output and look for the word *RECURSION*.



It's not an elegant solution, but it's the only one I've found, so I hope it helps someone.

kal at kalunite dot com i mean dot net
16-Jan-2007 05:55


About the automatic conversion of bare strings...

My opinion is that it never should have been implemented. Isn't it easier to NOT implement this "handy" feature in the first place? It is such a convenient way for "smart" programmers to write unsafe, not-futureproof code. Please remove this feature from future versions of PHP, please. (Hey, if you could change the OOP mechanisms between PHP 4 and PHP 5, why can't you make this change, right?)

25-Oct-2006 09:18


This page should include details about how associative arrays are implemened inside PHP; e.g. using hash-maps or b-trees.



This has important implictions on the permance characteristics of associative arrays and how they should be used; e.g. b-tree are slow to insert but handle collisions better than hashmaps.  Hashmaps are faster if there are no collisions, but are slower to retrieve when there are collisions.  These factors have implictions on how associative arrays should be used.

Mark Gukov
27-Sep-2006 02:18


Regarding the fact that there's no need to quote arrays keys when enclosed in double quotes: it only applies to single dimensional arrays.



The following works fine:



<?php

$r['a'] = 'apple';

echo "$r[a] is tasty.";

?>



...but in the case of multi-dimensional arrays:



<?php

$r['a']['b'] = 'banana';

echo "$r[a][b] is tasty.";

?>



would result in "Array[c] is tasty."

petruzanautico at yahoo dot com dot ar
21-Sep-2006 08:30


Regarding the message of phoenixbytes:



The line foreach($bad as $baddies); will just yield in $baddies the last value of the array $bad.

I think that wasn't your intention, in that case there are faster and better ways than foreach.



I think what you wanted to do is:

<?php

foreach($bad as $baddies) // make a collection

{

    if (preg_match("/$baddies/i", $mailto)) // find a match

    {

    $addrmail = "false";

    }

    else

    {

    $addrmail = "true";

    }

} // foreach end

?>

php dot net at todandlorna dot com
25-Jul-2006 04:28


in response to ch dot martin at gmail dot com



If you are using the following code:



<?php

$r = array('05' => "abc", '35' => "def");

foreach ($r as $key=>$value)

   var_dump($key);

?>



and you need the array key '35' to be a string (for looping maybe), you can make sure the key is a string by appending a 0 on the front.



'035' instead of '35'

ch dot martin at gmail dot com
08-Jun-2006 11:40


Extremely irritating quirk regarding the variable types of array keys:



<?php

$r = array('05' => "abc", '35' => "def");

foreach ($r as $key=>$value)

    var_dump($key);

?>



The first var_dump for '05' is:

    string(2) "05"

as expected.  But the second, '35', turns out as:

    int(35)



Php apparently decided to make the 35 became an int, but not the 05 (presumably because it leads with a zero).  As far as I can see, there is absolutely no way of making string(2) "35" an array key.

anghuda(at)gmail(dot)com
25-May-2006 06:52


this is simpler tha function display_angka_bilangan by ktaufik(at)gmail(dot)com (16-Feb-2005 12:40)



<?



/*

*

* Class : Terbilang

* Spell quantity numbers in Indonesian or Malay Language

*

*

* author: huda m elmatsani

* 21 September 2004

* freeware

*

* example:

* $bilangan = new Terbilang;

* echo $bilangan -> eja(137);

* result: seratus tiga puluh tujuh

*

*

*/



Class Terbilang {



    function terbilang() {

        $this->dasar = array(1=>'satu','dua','tiga','empat','lima','enam',

        'tujuh','delapan','sembilan');



        $this->angka = array(1000000000,1000000,1000,100,10,1);

        $this->satuan = array('milyar','juta','ribu','ratus','puluh','');

    }



    function eja($n) {



    $i=0;

    while($n!=0){



        $count = (int)($n/$this->angka[$i]);



        if($count>=10) $str .= $this->eja($count). " ".$this->satuan[$i]." ";

        else if($count > 0 && $count < 10)

            $str .= $this->dasar[$count] . " ".$this->satuan[$i]." ";



            $n -= $this->angka[$i] * $count;

            $i++;

        }

        $str = preg_replace("/satu puluh (\w+)/i","\\1 belas",$str);

        $str = preg_replace("/satu (ribu|ratus|puluh|belas)/i","se\\1",$str);



        return $str;

    }

}



?>

benjcarson at digitaljunkies dot ca
09-May-2006 01:46


phoenixbytes: The regex you have posted for matching email addresses is incorrect.  Among other things, it does not allow '+' before the '@' (which is perfectly valid and can be quite useful to separate extensions of a single address).  RFC 822 [1] defines the grammar for valid email addresses, and (the extemely long) regex implementing can be found at [2].  Even the "Add Note" page here at php.net says: 



[quote]

And if you're posting an example of validating email addresses, please don't bother. Your example is almost certainly wrong for some small subset of cases. See this information from O'Reilly Mastering Regular Expressions book for the gory details.

[/quote]



A note to others: please do your homework before writing another email-matching regex.



[1] http://www.ietf.org/rfc/rfc0822.txt?number=822

[2] http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html.

phoenixbytes at o2 dot co dot uk
16-Apr-2006 05:10


i use the array() function for deciding upon an email address's validity, i have a 'wap stalker' of my site that loves to exploit every hole i leave, so i used the following script to avoid being email bombed with my own file sender script, the array() is used to filter out undesirable email providers and, of course, any and all of my own addresses. before all that i used a REGEX to make sure it's an actual email address before going any further.



$mailto = "mail.domain.org"; // the input to be tested



if (preg_match("/^[A-Z0-9._%-]+@[A-Z0-9._%-]+\.[A-Z]{2,6}$/i", $mailto)) // see if it's really an email address

{

    $bad = array('mytrashmail.com', 'mymail.ro', 'acasa.ro', 'gala.net', 'phoenixbytes'); // pick out the victims

    foreach($bad as $baddies); // make a collection



    if (preg_match("/$baddies/i", $mailto)) // find a match

    {

    $addrmail = "false";

    }

    else

    {

    $addrmail = "true";

    }



}

else

{

$addrmail = "false"; 

}



$addrmail can then be used in an argument.

$baddies can be used to give a list, if necessary.



i hope this helps someone.

crozzer
01-Apr-2006 12:54


Passing variables into the array constructor:

Just a NOOB pointer, I couldn't find other examples for this.  If you want to pass the value of an existing variable into the array() constructor, you can quote it or not, both methods are valid.



<? 

$foo_value = 'foo string';

$bar_value = 'bar string';



$myArray = array(

    'foo_key' => $foo_value,     // not quoted

    'bar_key' => "$bar_value");   // quoted



foreach ($myArray as $k => $v) {

   echo "\$myArray[$k] => $v.<br />\n";

}

?>



Both of these will work as expected, but the unqoted $foo_value method above is marginally faster because adding quotes adds an additional string de-reference.

sales at maboom dot ch
13-Dec-2005 09:41


if you need to check a multidimensonal array for values it's handy to store it like 



$ar['key1'][0]

$ar['key2'][0] 

$ar['key3'][0]



$ar['key1'][1]

$ar['key2'][1] 

$ar['key3'][1]



and to loop the keys.



Fill the array (from a database-request):



while($rf=mysql_fetch_row($rs))



{

    $nr=$rf[0];

    $channel['nr'][$nr]=$rf[1];

    $channel['chatter'][$nr]=$rf[2];

}



Call the values:



foreach(array_keys($channel['nr']) as $test)

{

print ' nr:'.$test.'<br>';

print 'value nr: '.$channel['nr'][$test].'<br>';

print ' chatter: '.$channel['chatter'][$test].'<br>';

}



This is useful, if you have to look later for an element

inside the array:



if(in_array($new_value,$channel['nr'])) print 'do something.';



Hope this helps someone.

ia [AT] zoznam [DOT] sk
30-Sep-2005 02:55


Regarding the previous comment, beware of the fact that reference to the last value of the array remains stored in $value after the foreach:



<?php

foreach ( $arr as $key => &$value )

{

    $value = 1;

}



// without next line you can get bad results...

//unset( $value );



$value = 159;

?>



Now the last element of $arr has the value of '159'. If we remove the comment in the unset() line, everything works as expected ($arr has all values of '1').



Bad results can also appear in nested foreach loops (the same reason as above).



So either unset $value after each foreach or better use the longer form:



<?php

foreach ( $arr as $key => $value )

{

    $arr[ $key ] = 1;

}

?>

stochnagara at hotmail dot com
27-Sep-2005 01:53


Regarding the previous comment, thw following code does the job:



<?php

foreach($arr as $key => &$value) {

   $value = 1;

}

?>

jazepstein OverAt GeeMail dot com
19-Sep-2005 06:14


Regarding the previous comment, the fact that this code has no effect is perfectly expected:



<?php

foreach($arr as $value) {

   $value = 1;

}

?>



The reason that this doesn't work, is because each time that PHP goes through the loop, it _copies_ the value of the array element into $value. So if you assign a new value to the data in $value, it has no effect on the actual array, because you only changed the value of the copy that was put in $value.



As was discovered in the previous post, the only way to get around this problem is to change the value in the original array. Hence, a typical foreach should instead look like this:



<?php

foreach($arr as $key => $value) {

   $arr[$key] = 1;

}

?>

caifara aaaat im dooaat be
28-Aug-2005 02:28


[Editor's note: You can achieve what you're looking for by referencing $single, rather than copying it by value in your foreach statement. See http://php.net/foreach for more details.]





Don't know if this is known or not, but it did eat some of my time and maybe it won't eat your time now...





I tried to add something to a multidimensional array, but that didn't work at first, look at the code below to see what I mean:





<?php





$a1 = array( "a" => 0, "b" => 1 );


$a2 = array( "aa" => 00, "bb" => 11 );





$together = array( $a1, $a2 );





foreach( $together as $single ) {


    $single[ "c" ] = 3 ;


}





print_r( $together ); 


/* nothing changed result is:


Array


(


    [0] => Array


        (


            [a] => 0


            [b] => 1


        )


    [1] => Array


        (


            [aa] => 0


            [bb] => 11


        )


) */





foreach( $together as $key => $value ) {


    $together[$key]["c"] = 3 ;


}





print_r( $together );





/* now it works, this prints


Array


(


    [0] => Array


        (


            [a] => 0


            [b] => 1


            [c] => 3


        )


    [1] => Array


        (


            [aa] => 0


            [bb] => 11


            [c] => 3


        )


)


*/





?>

uzakufuklar at hotmail dot com
03-Aug-2005 11:24


It is a kind of simple muti-dimensional array list.

 I have made it just to give a simple idea.

<?php 

echo "Here we'll see how to create a multi-dimensional array.\n";

$a=array('fruits'=>array('a'=>'orange',

                      'b'=>'grape',c=>'apple'),

            'numbers'=>array(1,2,3,4,5,6),

            'holes'=>array('first',5=>'second',

                                                          'third')

            );

foreach($a as $list=>$things){

    foreach($things as $newlist=>$counter){

    echo $counter;

    }

}

?>

z
22-Apr-2005 12:10


Here's a simple function to insert a value into some position in an array



<?php

function array_insert($array,$pos,$val)

{

    $array2 = array_splice($array,$pos);

    $array[] = $val;

    $array = array_merge($array,$array2);

    

    return $array;

}

?>



and now for example...

<?php

$a = array("John","Paul","Peter");

$a = array_insert($a,1,"Mike");

?>



Now $a will be "John","Mike","Paul","Peter"

jeff splat codedread splot com
21-Apr-2005 09:16


Beware that if you're using strings as indices in the $_POST array, that periods are transformed into underscores:



<html>

<body>

<?php

    printf("POST: "); print_r($_POST); printf("<br/>");

?>

<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">

    <input type="hidden" name="Windows3.1" value="Sux">

    <input type="submit" value="Click" />

</form>

</body>

</html>



Once you click on the button, the page displays the following:



POST: Array ( [Windows3_1] => Sux )

roland dot swingler at transversal dot com
05-Apr-2005 08:24


Something that tripped me u