PHP array_pad() Function

The array_pad() is a builtin function in PHP and is used to pad a value fixed number of time onto an array. This function inserts an element specified number of times into an array either at front or back. Syntax:

array array_pad($input_array, $input_size, $values)

Parameters: This function accepts three parameters, all of this which are mandatory to be supplied.

1. $input_array (mandatory): Refers to the array, on which the operation is to be performed, or to which the elements are needed to be added.
2. $total_size (mandatory): Refers to the total size of the new array to be returned.
   • If the value is positive, the elements get added to the end of the array.
   • If the value is negative, the elements get added at the beginning of the array.
3. $values (mandatory): Refers to the value with which padding will take place. The padding takes place only when $total_size is greater than the size of the input_array.

Return Value: The function returns a copy of the array padded to the size of $total_size. If the absolute value of $total_size is less than or equal to the length of the array then no padding takes place. It is possible to add, at most 1048576 elements at a time. Examples:

Input : array = ("one", "two", "three", "four", "five")
        $total_size  = 7 , $value = "six"
Output : 
Array
(
    [0] => one
    [1] => two
    [2] => three
    [3] => four
    [4] => five
    [5] => six
    [6] => six
)

Input : array = ("one", "two", "three", "four", "five")
        $total_size  = -7 , $value = "six"
Output : 
Array
(
    [0] => six
    [1] => six
    [2] => one
    [3] => two
    [4] => three
    [5] => four
    [6] => five
)

Below programs explains the working of the array_pad() function:

1. Padding elements at end of the array when the $total_size is positive:

   <?php
   // PHP function to illustrate the use of array_pad()
   function Padding($array, $string)
   {
       $result = array_pad($array, 7, $string);
       return($result);
   }
   
   $array = array("one", "two", "three", "four", "five");
   $string = "six";
   print_r(Padding($array, $string));
   ?>
   

   Output:

   Array
   (
       [0] => one
       [1] => two
       [2] => three
       [3] => four
       [4] => five
       [5] => six
       [6] => six
   )
   

2. Padding elements at start of the array when the $total_size is negative:

   <?php
   // PHP function to illustrate the use of array_pad()
   function Padding($array, $string)
   {
       $result = array_pad($array, -7, $string);
       return($result);
   }
   
   $array = array("one", "two", "three", "four", "five");
   $string = "six";
   print_r(Padding($array, $string));
   ?>
   

   Output:

   Array
   (
       [0] => six
       [1] => six
       [2] => one
       [3] => two
       [4] => three
       [5] => four
       [6] => five
   )