- print_r: documentation ( source)
- implode: documentation ( source)
- preg_split: documentation ( source)
<?php
$foo = 'hello form world. i am windows. i am linux; I and me! You and I; ponies?';
$foos=preg_split('/(?<=[.;!?]\s)(?=[a-z])/',$foo);
print_r($foos); //only needed split
foreach ($foos as &$f) $f[0]=$f[0]^' '; //xor it uppercase
$foo=implode(' ',$foos);
print '<br>'.$foo;