array_pad

(PHP 4, PHP 5, PHP 7, PHP 8)

array_pad — 指定長、指定した値で配列を埋める

説明

array_pad(array $array, int $length, mixed $value): array

array_pad() は、length で指定した長さになるように値 value で埋めて array のコピーを返します。 length が正の場合、配列の右側が埋められます。負の場合、配列の左側が埋められます。 length の絶対値が array の長さ以下の場合、埋める処理は行われません。

パラメータ

array: 値を埋めるもととなる配列。
length: 新しい配列のサイズ。
value: array が length より小さいときに、埋めるために使用する値。

戻り値

length で指定した長さになるように値 value で埋めて array のコピーを返します。 length が正の場合、配列の右側が埋められます。負の場合、配列の左側が埋められます。 length の絶対値が array の長さ以下の場合、埋める処理は行われません。

変更履歴

バージョン	説明
8.3.0	PHP 8.3 より前のバージョンでは、一度に 1048576 個の要素しか追加できませんでした。このバージョンからは、制限は配列の最大サイズのみになりました。

例

例1 array_pad() の例

<?php
$input = array(12, 10, 9);

$result = array_pad($input, 5, 0);
// 結果は、array(12, 10, 9, 0, 0) です。

$result = array_pad($input, -7, -1);
// 結果は、array(-1, -1, -1, -1, 12, 10, 9) です。

$result = array_pad($input, 2, "noop");
// 埋める処理は行われません。
?>

参考

array_fill() - 配列を指定した値で埋める
range() - ある範囲の要素を含む配列を作成する

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User Contributed Notes 8 notes

down

tugla ¶

16 years ago

Beware, if you try to pad an associative array using numeric keys, your keys will be re-numbered.



<?php

$a = array('size'=>'large', 'number'=>20, 'color'=>'red');

print_r($a);

print_r(array_pad($a, 5, 'foo'));



// use timestamps as keys

$b = array(1229600459=>'large', 1229604787=>20, 1229609459=>'red');

print_r($b);

print_r(array_pad($b, 5, 'foo'));

?>



yields this:

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

Array

(

    [size] => large

    [number] => 20

    [color] => red

)

Array

(

    [size] => large

    [number] => 20

    [color] => red

    [0] => foo

    [1] => foo

)

Array

(

    [1229600459] => large

    [1229604787] => 20

    [1229609459] => red

)

Array

(

    [0] => large

    [1] => 20

    [2] => red

    [3] => foo

    [4] => foo

)

down

goffrie at sympatico dot ca ¶

22 years ago

To daarius - you mean you have...



[2]=>"two"

[3]=>"three"



and you want...



[0]=>"FILLED"

[1]=>"FILLED"

[2]=>"two"

[3]=>"three"

[4]=>"FILLED"

[5]=>"FILLED"



If so, then the following code...



<?php

$array = array(2 => "two", 3 => "three");

$array = array_pad($array, count($array)+2, "FILLED");

$num = -(count($array)+2);

$array = array_pad($array, $num, "FILLED");

print_r($array);

?>



will return:

Array ( [0] => FILLED [1] => FILLED [2] => two [3] => three [4] => FILLED [5] => FILLED )

The ordering should be okay,...

down

scott*hurring.com ¶

22 years ago

to the previous commenter -- if you read the manual entry, you'd see that a negative pad_size will put the pad values at the front of the array.

down

mwwaygoo at hotmail dot com ¶

21 years ago

little older, a little wiser.



ksort() will order the array back into its normal order again

so:



<?php

$myArr = array(2 => 'two', 4 => 'four');



$newArr = array_pad(array(), 6, 'FILLED');

$newArr =$myArr+$newArr;

ksort($newArr);

?>



Will give : 

Array ( [0] => FILLED [1] => FILLED [2] => two [3] => FILLED [4] => four [5] => FILLED )

down

Anonymous ¶

21 years ago

One way to initialize a 20x20 multidimensional array.  



<?php

$a = array();

$b = array();

$b = array_pad($b,20,0);

$a = array_pad($a,20,$b);

?>

down

-1

hk, StrApp Bussiness Solutions ¶

18 years ago

A simple example for array_pad()

the syntax is as follows: array_pad(array(), (+/-)int, value)

where "array" is the array to which the value is to be added,

"(+/-) int" is a value that decides the length of the array(it should be greater than the length of the array.
if its a negative number then the value will be added at the left of the array else it will be added to the right.

"values" denotes the value to be added to the array

lets try an example:

<?php

$digits = array();
$digits[0] = 1;
$digits[1] = 2;
$digits[2] = 3;
$arraypad = array_pad($digits, -4, "0");
print_r($arraypad);

?>

output:

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

down

-2

daarius at hotmail dot com ¶

22 years ago

yes that is true. But, if the index of the array is 2=two, 3=three

and i want 4 more keys to be filled. But, not just filled anywhere, but i want to maintain the key index.

so, i would like to have 0=FILLED, 1=FILLED ... 4=FILLED, 5=FILLED

now i got 4 more keys padded with my string.

We can do this "if" we know the missing keys, but if we dont, then it would be nice for array_pad() or perhaps some new function to do this?

obviously we can achive this by looping through the array using array_key_exists(), and if you dont find the key, simply create + fill it.
regards,
Daarius...

down

-3

mwwaygoo at hotmail dot com ¶

22 years ago

OR you could do this 



<?php

$myArr = array(2 => 'three', 3 => 'four');



$newArr = array_pad(array(), 4, 'FILLED');

$newArr =$myArr+$newArr;

?>



This gives your desired result BUT the ordering is a little wierd, because of the order they were added. Indexes are okay though and that is what you wanted.



print_r($newArr) outputs

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



hope this helps

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