<?php
$str = "ExplodeAtCapitalLetters";
$str[0] = strtolower($str[0]);
$pieces = preg_split('/(?=[A-Z])/',$str);
$pieces[0][0] = strtoupper($pieces[0][0]);
print_r($pieces);
Array
(
[0] => Explode
[1] => At
[2] => Capital
[3] => Letters
)
$str = "ExplodeAtCapitalLetters";
$str[0] = strtolower($str[0]);
$pieces = preg_split('/(?=[A-Z])/',$str);
$pieces[0][0] = strtoupper($pieces[0][0]);
print_r($pieces);
Array
(
[0] => Explode
[1] => At
[2] => Capital
[3] => Letters
)