list(3) [php man page]

LIST(3) 								 1								   LIST(3)

list - Assign variables as if they were an array

SYNOPSIS

       array list (mixed  $var1, [mixed  $...])

DESCRIPTION

	Like array(3), this is not really a function, but a language construct. list(3) is used to assign a list of variables in one operation.

PARAMETERS

	      o $var1
		- A variable.

RETURN VALUES

	Returns the assigned array.

EXAMPLES

       Example #1

	      list(3) examples

	      <?php

	      $info = array('coffee', 'brown', 'caffeine');

	      // Listing all the variables
	      list($drink, $color, $power) = $info;
	      echo "$drink is $color and $power makes it special.
";

	      // Listing some of them
	      list($drink, , $power) = $info;
	      echo "$drink has $power.
";

	      // Or let's skip to only the third one
	      list( , , $power) = $info;
	      echo "I need $power!
";

	      // list() doesn't work with strings
	      list($bar) = "abcde";
	      var_dump($bar); // NULL
	      ?>

       Example #2

	      An example use of list(3)

	      <table>
	       <tr>
		<th>Employee name</th>
		<th>Salary</th>
	       </tr>

	      <?php
	      $result = $pdo->query("SELECT id, name, salary FROM employees");
	      while (list($id, $name, $salary) = $result->fetch(PDO::FETCH_NUM)) {
		  echo " <tr>
" .
			"  <td><a href="info.php?id=$id">$name</a></td>
" .
			"  <td>$salary</td>
" .
			" </tr>
";
	      }

	      ?>

	      </table>

       Example #3

	      Using nested list(3)

	      <?php

	      list($a, list($b, $c)) = array(1, array(2, 3));

	      var_dump($a, $b, $c);

	      ?>

	      int(1)
	      int(2)
	      int(3)

       Example #4

	      Using list(3) with array indices

	      <?php

	      $info = array('coffee', 'brown', 'caffeine');

	      list($a[0], $a[1], $a[2]) = $info;

	      var_dump($a);

	      ?>

	       Gives the following output (note the order of the elements compared in which order they were written in the list(3) syntax):

	      array(3) {
		[2]=>
		string(8) "caffeine"
		[1]=>
		string(5) "brown"
		[0]=>
		string(6) "coffee"
	      }

NOTES

       Warning

	      list(3)  assigns	the values starting with the right-most parameter. If you are using plain variables, you don't have to worry about
	      this. But if you are using arrays with indices you usually expect the order of the indices in the array the same you  wrote  in  the
	      list(3) from left to right; which it isn't. It's assigned in the reverse order.

       Warning

	       Modification of the array during list(3) execution (e.g. using list($a, $b) = $b) results in undefined behavior.

       Note

	      list(3) only works on numerical arrays and assumes the numerical indices start at 0.

SEE ALSO

       each(3), array(3), extract(3).

PHP Documentation Group 														   LIST(3)

ARRAY_MAP(3)								 1							      ARRAY_MAP(3)

array_map - Applies the callback to the elements of the given arrays

SYNOPSIS

       array array_map (callable  $callback, array  $array1, [array  $...])

DESCRIPTION

       array_map(3)  returns  an  array  containing  all  the elements of $array1 after applying the $callback function to each one. The number of
       parameters that the $callback function accepts should match the number of arrays passed to the array_map(3)

PARAMETERS

	      o $callback
		- Callback function to run for each element in each array.

	      o $array1
		- An array to run through the $callback function.

	      o $...
		- Variable list of array arguments to run through the $callback function.

RETURN VALUES

	Returns an array containing all the elements of $array1 after applying the $callback function to each one.

EXAMPLES

       Example #1

	      array_map(3) example

	      <?php
	      function cube($n)
	      {
		  return($n * $n * $n);
	      }

	      $a = array(1, 2, 3, 4, 5);
	      $b = array_map("cube", $a);
	      print_r($b);
	      ?>

	       This makes $b have:

	      Array
	      (
		  [0] => 1
		  [1] => 8
		  [2] => 27
		  [3] => 64
		  [4] => 125
	      )

       Example #2

	      array_map(3) using a lambda function (as of PHP 5.3.0)

	      <?php
	      $func = function($value) {
		  return $value * 2;
	      };

	      print_r(array_map($func, range(1, 5)));
	      ?>

	      Array
	      (
		  [0] => 2
		  [1] => 4
		  [2] => 6
		  [3] => 8
		  [4] => 10
	      )

       Example #3

	      array_map(3) - using more arrays

	      <?php
	      function show_Spanish($n, $m)
	      {
		  return("The number $n is called $m in Spanish");
	      }

	      function map_Spanish($n, $m)
	      {
		  return(array($n => $m));
	      }

	      $a = array(1, 2, 3, 4, 5);
	      $b = array("uno", "dos", "tres", "cuatro", "cinco");

	      $c = array_map("show_Spanish", $a, $b);
	      print_r($c);

	      $d = array_map("map_Spanish", $a , $b);
	      print_r($d);
	      ?>

	      The above example will output:

	      // printout of $c
	      Array
	      (
		  [0] => The number 1 is called uno in Spanish
		  [1] => The number 2 is called dos in Spanish
		  [2] => The number 3 is called tres in Spanish
		  [3] => The number 4 is called cuatro in Spanish
		  [4] => The number 5 is called cinco in Spanish
	      )

	      // printout of $d
	      Array
	      (
		  [0] => Array
		      (
			  [1] => uno
		      )

		  [1] => Array
		      (
			  [2] => dos
		      )

		  [2] => Array
		      (
			  [3] => tres
		      )

		  [3] => Array
		      (
			  [4] => cuatro
		      )

		  [4] => Array
		      (
			  [5] => cinco
		      )

	      )

	Usually when using two or more arrays, they should be of equal length because the callback function is applied in parallel to  the  corre-
       sponding  elements. If the arrays are of unequal length, shorter ones will be extended with empty elements to match the length of the long-
       est.

	An interesting use of this function is to construct an array of arrays, which can be easily performed by using NULL as	the  name  of  the
       callback function

       Example #4

	      Creating an array of arrays

	      <?php
	      $a = array(1, 2, 3, 4, 5);
	      $b = array("one", "two", "three", "four", "five");
	      $c = array("uno", "dos", "tres", "cuatro", "cinco");

	      $d = array_map(null, $a, $b, $c);
	      print_r($d);
	      ?>

	      The above example will output:

	      Array
	      (
		  [0] => Array
		      (
			  [0] => 1
			  [1] => one
			  [2] => uno
		      )

		  [1] => Array
		      (
			  [0] => 2
			  [1] => two
			  [2] => dos
		      )

		  [2] => Array
		      (
			  [0] => 3
			  [1] => three
			  [2] => tres
		      )

		  [3] => Array
		      (
			  [0] => 4
			  [1] => four
			  [2] => cuatro
		      )

		  [4] => Array
		      (
			  [0] => 5
			  [1] => five
			  [2] => cinco
		      )

	      )

	If the array argument contains string keys then the returned array will contain string keys if and only if exactly one array is passed. If
       more than one argument is passed then the returned array always has integer keys.

       Example #5

	      array_map(3) - with string keys

	      <?php
	      $arr = array("stringkey" => "value");
	      function cb1($a) {
		  return array ($a);
	      }
	      function cb2($a, $b) {
		  return array ($a, $b);
	      }
	      var_dump(array_map("cb1", $arr));
	      var_dump(array_map("cb2", $arr, $arr));
	      var_dump(array_map(null,	$arr));
	      var_dump(array_map(null, $arr, $arr));
	      ?>

	      The above example will output:

	      array(1) {
		["stringkey"]=>
		array(1) {
		  [0]=>
		  string(5) "value"
		}
	      }
	      array(1) {
		[0]=>
		array(2) {
		  [0]=>
		  string(5) "value"
		  [1]=>
		  string(5) "value"
		}
	      }
	      array(1) {
		["stringkey"]=>
		string(5) "value"
	      }
	      array(1) {
		[0]=>
		array(2) {
		  [0]=>
		  string(5) "value"
		  [1]=>
		  string(5) "value"
		}
	      }

SEE ALSO

       array_filter(3), array_reduce(3), array_walk(3), information about the callback type.

PHP Documentation Group 													      ARRAY_MAP(3)