(PHP 5)
str_split — Convert a string to an array
$string
   [, int $split_length = 1
  ] )Converts a string to an array.
stringThe input string.
split_lengthMaximum length of the chunk.
   If the optional split_length parameter is
   specified, the returned array will be broken down into chunks with each
   being split_length in length, otherwise each chunk
   will be one character in length.
  
   FALSE is returned if split_length is less than 1.
   If the split_length length exceeds the length of
   string, the entire string is returned as the first
   (and only) array element.
  
Example #1 Example uses of str_split()
<?php
$str = "Hello Friend";
$arr1 = str_split($str);
$arr2 = str_split($str, 3);
print_r($arr1);
print_r($arr2);
?>
The above example will output:
Array
(
    [0] => H
    [1] => e
    [2] => l
    [3] => l
    [4] => o
    [5] =>
    [6] => F
    [7] => r
    [8] => i
    [9] => e
    [10] => n
    [11] => d
)
Array
(
    [0] => Hel
    [1] => lo
    [2] => Fri
    [3] => end
)
Note:
str_split() will split into bytes, rather than characters when dealing with a multi-byte encoded string.