split php string into chunks of varying length

Question

I am looking for ways to split a string into an array, sort of str_split(), where the chunks are all of different sizes.

I could do that by looping through the string with a bunch of substr(), but that looks neither elegant nor efficient. Is there a function that accept a string and an array, like (1, 18, 32, 41, 108, 125, 137, 152, 161), and yields an array of appropriately chopped string pieces?

Explode is inappropriate because the chunks are delimited by varying numbers of white spaces.

Answer 1

I would use unpack():

$str = "?ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890....";
$array = unpack("a1first/a26second/a10third/a*rest",$str);
print_r($array);

This returns:

Array
(
    [first] => ?
    [second] => ABCDEFGHIJKLMNOPQRSTUVWXYZ
    [third] => 1234567890
    [rest] => ....
)

Answer 2

Just for future references the regular expressions method @jay suggested goes like this:

 $regex="/(.{1})(.{18})(.{32})(.{41})(.{108})(.{125})(.{137})(.{152})(.{161})/";
 preg_match($regex,$myfixedlengthstring,$arr);

where $myfixedlengthstring is the target string and $arr gives you the result