array_pad

说明

array array_pad ( array input, int pad_size, mixed pad_value )

array_pad() 返回 input 的一个拷贝，并用 pad_value 将其填补到 pad_size 指定的长度。如果 pad_size 为正，则数组被填补到右侧，如果为负则从左侧开始填补。如果 pad_size 的绝对值小于或等于 input 数组的长度则没有任何填补。有可能一次最多填补 1048576 个单元。

例 1. array_pad() 例子


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

$result = array_pad($input, 5, 0);
// result is array(12, 10, 9, 0, 0)

$result = array_pad($input, -7, -1);
// result is array(-1, -1, -1, -1, 12, 10, 9)

$result = array_pad($input, 2, "noop");
// not padded
?>

参见 array_fill() 和 range()。

add a note User Contributed Notes

hk, StrApp Bussiness Solutions
08-Jan-2007 10:15


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 )

oaev at mail dot ru
22-Oct-2004 06:48


Easy way to get an array contains 5 random numbers from 0 to 9:



$rand_arr = array_rand( array_pad( array(), 10, 1 ), 5 );

29-Feb-2004 05:00


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);


?>

mwwaygoo at hotmail dot com
16-Jan-2004 04:02


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 )

goffrie at sympatico dot ca
24-Mar-2003 01:06


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,...

mwwaygoo at hotmail dot com
19-Sep-2002 04:39


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

daarius at hotmail dot com
23-Jul-2002 02:36


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...

scott*hurring.com
19-Jul-2002 11:20


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.

ethanhunt314 at hotmail dot com
10-Dec-2000 12:25


This is useful when using next() and prev() function in a while loop to traverse an array. 





For example the following code will only output up to 8.





<?php


$test[] = "1";


$test[] = "2";


$test[] = "3";


$test[] = "4";


$test[] = "5";


$test[] = "6";


$test[] = "7";


$test[] = "8";


$test[] = "9";


$test[] = "10";


$test[] = " ";


$test[] = " ";


$test[] = " ";





$count = count($test);





while($i < $count) {





$now = current($test);


echo "<p>$now</p>";





next($test);


next($test);


next($test);


prev($test);


prev($test);


prev($test);








$i++;


next($test);


}


?>





But if you use:


$test = array_pad($test, 13, " ");





you will get all of your output.

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