array_pad

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

    array_pad — Pad array to the specified length with a value

    Description

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

    array_pad() returns a copy of the array padded to size specified by length with value value. If length is positive then the array is padded on the right, if it's negative then on the left. If the absolute value of length is less than or equal to the length of the array then no padding takes place.

    Parameters

    array

    Initial array of values to pad.

    length

    New size of the array.

    value

    Value to pad if array is less than length.

    Return Values

    Returns a copy of the array padded to size specified by length with value value. If length is positive then the array is padded on the right, if it's negative then on the left. If the absolute value of length is less than or equal to the length of the array then no padding takes place.

    Changelog

    Version Description
    8.3.0 Prior to 8.3, only 1048576 elements could be added at once. Now it is limited only by the maximum size of an array instead.

    Examples

    Example #1 array_pad() example

    <?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
    ?>

    See Also

    • array_fill() - Fill an array with values
    • range() - Create an array containing a range of elements

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    User Contributed Notes 11 notes

    up
    22
    tugla
    15 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
    )
    up
    11
    goffrie at sympatico dot ca
    21 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,...
    up
    7
    scott*hurring.com
    21 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.
    up
    6
    mwwaygoo at hotmail dot com
    20 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 )
    up
    3
    Anonymous
    20 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);
    ?>
    up
    -1
    hk, StrApp Bussiness Solutions
    17 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 )
    up
    -2
    daarius at hotmail dot com
    21 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...
    up
    -3
    mwwaygoo at hotmail dot com
    21 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
    up
    -7
    oaev at mail dot ru
    19 years ago
    Easy way to get an array contains 5 random numbers from 0 to 9:

    $rand_arr = array_rand( array_pad( array(), 10, 1 ), 5 );
    up
    -7
    slava-san at mail dot ru
    11 years ago
    // insert element to array
    function array_insert(&$arr, $pos, $new_el=null) {
    $arraypad = array_pad($arr, count($arr)+1, 0);
    for ($i=count($arr)-1; $i>=$pos; $i--) {
    $arr[$i+1] = $arr[$i];
    if ($i == $pos) {
    $arr[$i] = $new_el;
    }
    }
    }

    $digits = array();
    $digits[0] = 0;
    $digits[1] = 1;
    $digits[2] = 2;
    $digits[3] = 3;
    $digits[4] = 4;
    $digits[5] = 5;
    echo "was: "; var_dump($digits);

    array_insert($digits, 3, 100);
    echo "new: "; var_dump($digits);
    up
    -12
    sonu50imedbvu at gmail dot com(Sonu Jaiswal)
    13 years ago
    Just an info about the value of "$pad_size" ,

    If we set the value of "$pad_size" from -3 to 3,

    It will produce the output like:

    <?php
    $result     = array_pad($input, -3, "noop");
    //result is array(12, 10, 9)

    $result = array_pad($input, 3, "noop");
    //result is array(12, 10, 9)
    ?>

    means array will remain the same.
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