array_fill

(PHP 4 >= 4.2.0, PHP 5, PHP 7)

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。

参数

start_index

返回的数组的第一个索引值。

如果 start_index 是负数，那么返回的数组的第一个索引将会是 start_index ，而后面索引则从0开始。 (参见例子)。

num

插入元素的数量。必须大于 0。

value

用来填充的值。

返回值

返回填充后的数组。

错误／异常

如果 num 少于一个，将会抛出 E_WARNING 。

范例

Example #1 array_fill() 例子

  <?php
$a  =  array_fill ( 5 ,  6 ,  'banana' );
 $b  =  array_fill (- 2 ,  4 ,  'pear' );
 print_r ( $a );
 print_r ( $b );
 ?>

以上例程会输出：

Array
(
    [5]  => banana
    [6]  => banana
    [7]  => banana
    [8]  => banana
    [9]  => banana
    [10] => banana
)
Array
(
    [-2] => pear
    [0] => pear
    [1] => pear
    [2] => pear
)

注释

参见手册上数组一节里关于负数的键的详细解释。

参见

array_fill_keys() - 使用指定的键和值填充数组
str_repeat() - 重复一个字符串
range() - 建立一个包含指定范围单元的数组

用户评论:

[#1] anatoliy at ukhvanovy dot name [2014-06-16 10:00:46]

If you need negative indices:
<?php $b = array_fill(-2, 4, 'pear');//this is not what we want $c = array_fill_keys(range(-2,1),'pear');//these are negative indices print_r($b); print_r($c); ?>
Here is result of the code above:
Array
(
    [-2] => pear
    [0] => pear
    [1] => pear
    [2] => pear
)
Array
(
    [-2] => pear
    [-1] => pear
    [0] => pear
    [1] => pear
)

[#2] mchljnk at NOSPAM dot gmail dot com [2013-11-10 03:07:07]

Using objects with array_fill may cause unexpected results. Consider the following:

<?php class Foo { public $bar = "banana"; } //fill an array with objects $array = array_fill(0, 2, new Foo()); var_dump($array); //now we change the attribute of the object stored in index 0 //this actually changes the attribute for EACH object in the ENTIRE array $array[0]->bar = "apple"; var_dump($array); ?>

Objects are filled in the array BY REFERENCE. They are not copied for each element in the array.

[#3] miguelxpain at gmail dot com [2012-02-24 18:04:55]

I made this function named "array_getMax" that returns te maximum value and index, from array:

<?php //using array_search_all by helenadeus at gmail dot com function array_search_all($needle, $haystack) {#array_search_match($needle, $haystack) returns all the keys of the values that match $needle in $haystack foreach ($haystack as $k=>$v) { if($haystack[$k]==$needle){ $array[] = $k; } } return ($array); } function array_getMax($array){ $conteo=array_count_values($array); if( count($conteo)==1 ){//returns full array when all values are the same. return $array; } arsort($array); //$antValue=null; $maxValue=null; $keyValue=null; foreach($array as $key=>$value){ if($maxValue==null){ $maxValue=$value; $keyValue=$key; break; } } $resultSearch=array_search_all($maxValue, $array); return array_fill_keys($resultSearch, $maxValue); } //example $arreglo=array('e1'=>99,'e2'=>'99','e3'=>1,'e4'=>1,'e5'=>98); var_dump(array_getMax($arreglo)); //output ?>

I hope some one find this usefull

[#4] csst0266 at cs dot uoi dot gr [2004-08-11 10:32:39]

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.

[#5] [2002-08-25 13:59:46]

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.