array_fill 用给定的值填充数组

转自：http://www.phpstudy.net/php/165.html

PHP array_fill 用给定的值填充数组

array_fill

(PHP 4 >= 4.2.0, PHP 5)

array_fill — 用给定的值填充数组

说明

array array_fill ( int $start_index , int $num , mixed $value )

array_fill() 用 value 参数的值将一个数组填充 num 个条目，键名由 start_index 参数指定的开始。注意 num 必须是一个大于零的数值，否则 PHP 会发出一条警告。

Example #1 array_fill() 例子

<?php
$a = array_fill(5, 6, 'banana');
print_r($a);
?>

$a 现在是：

Array
(
    [5]  => banana
    [6]  => banana
    [7]  => banana
    [8]  => banana
    [9]  => banana
    [10] => banana
)

参见 str_repeat() 和 range()。

 

« array_diff_ukeyarray_fill_keys »

 

PHP array_fill note #1

To better handle the problem of sparse array completion mentioned a couple years ago...

What you really need in this scenario is an empty array containing all the desired keys, and a sparse array containing the keys and values you want overridden. This PHP5 function does that. (The PEAR package PHP_Compat should be able to fill in the gap -- array_combine() --  for a 4.3 install, if necessary.)

<?php
    function array_complete(
        $keys="",                // array of keys you need filled, in order
        $sparse=""                // sparse array to override blanks
    )
    {
        if(!is_array($sparse)) 
            $sparse=array();
    
        if(!is_array($keys))
            return $sparse;
    
        return array_merge(        
            array_combine(        // create an associative array
                $keys,            // your list of keys
                array_fill(        // blank value for each key
                    0,count(
                        $keys
                    ),""
                )
            ),$sparse            // merge with your incomplete array
        );
    }
?>

This merges in your sparse array (inserting any additional keys in that array after the ones you've specified), placing its values in the key order you specify, leaving all the other values blank.

Test call: var_dump(array_complete(array("test1", "test2", "test3", "test4", "test5"), array("test3" => "test3", "test1" => "test1", "garbage" => "garbage")));

Result: array(6) {
  ["test1"]=>
  string(5) "test1"
  ["test2"]=>
  string(0) ""
  ["test3"]=>
  string(5) "test3"
  ["test4"]=>
  string(0) ""
  ["test5"]=>
  string(0) ""
  ["garbage"]=>
  string(7) "garbage"
}

PHP array_fill note #2

This is what I recently did to quickly create a two dimensional array (10x10), initialized to 0:

<?php
  $a = array_fill(0, 10, array_fill(0, 10, 0));
?>

This should work for as many dimensions as you want, each time passing to array_fill() (as the 3rd argument) another array_fill() function.

PHP array_fill note #3

For PHP < 4.2.0 users:

Add this to your script:
if (!function_exists('array_fill')) {
   require_once('array_fill.func.php');
}

and the array_fill.func.php file:

<?php

// For PHP version < 4.2.0 missing the array_fill function,
// I provide here an alternative. -Philippe

function array_fill($iStart, $iLen, $vValue) {
    $aResult = array();
    for ($iCount = $iStart; $iCount < $iLen + $iStart; $iCount++) {
        $aResult[$iCount] = $vValue;
    }
    return $aResult;
}

?>

PHP array_fill note #4

array_fill() cannot be used to setup only missing keys in an array. This  may be necessary for example before using implode()  on a sparse filled array. 
The solution is to use this function:

<?php 
function array_setkeys(&$array, $fill = NULL) { 
  $indexmax = -1; 
  for (end($array); $key = key($array); prev($array)) { 
    if ($key > $indexmax) 
      $indexmax = $key; 
  } 
  for ($i = 0; $i <= $indexmax; $i++) { 
    if (!isset($array[$i])) 
      $array[$i] = $fill; 
  } 
  ksort($array); 
} 
?>

This is usefull in some situations where you don't know which key index was filled and you want to preserve the association between a positioned field in an imploded array and the key index when exploding it.