Most efficient way to delimit key.

Question

Say I have a string of 16 numeric characters (i.e. 0123456789012345) what is the most efficient way to delimit it into sets like : 0123-4567-8901-2345, in PHP?

Note: I am rewriting an existing system that is painfully slow.

Answer 1

Use str_split():

$string = '0123456789012345';
$sets = str_split($string, 4);
print_r($sets);

The output:

Array
(
    [0] => 0123
    [1] => 4567
    [2] => 8901
    [3] => 2345
)

Then of course to insert hyphens between the sets you just implode() them together:

echo implode('-', $sets); // echoes '0123-4567-8901-2345'

Answer 2

If you are looking for a more flexible approach (for e.g. phone numbers), try regular expressions:

preg_replace('/^(\d{4})(\d{4})(\d{4})(\d{4})$/', '\1-\2-\3-\4', '0123456789012345');

If you can't see, the first argument accepts four groups of four digits each. The second argument formats them, and the third argument is your input.

Answer 3

This is a bit more general:

<?php

// arr[string] = strChunk(string, length [, length [...]] );
function strChunk() {
    $n = func_num_args();
    $str = func_get_arg(0);
    $ret = array();

    if ($n >= 2) {
     for($i=1, $offs=0; $i<$n; ++$i) {
      $chars = abs( func_get_arg($i) );
      $ret[] = substr($str, $offs, $chars);
      $offs += $chars;
     }
    }

    return $ret;
}

echo join('-', strChunk('0123456789012345', 4, 4, 4, 4) );

?>