<?php

if(!function_exists('mb_ucfirst'))
{
    function mb_ucfirst($string, $enc = 'UTF-8')
    {
        return mb_strtoupper(mb_substr($string, 0, 1, $enc), $enc) .
            mb_substr($string, 1, mb_strlen($string, $enc), $enc);
    }
}
function sentence_case($string) { 
    $sentences = preg_split('/([.?!]+)/', $string, -1, PREG_SPLIT_NO_EMPTY|PREG_SPLIT_DELIM_CAPTURE); 
    $new_string = ''; 
    foreach ($sentences as $key => $sentence) { 
        $new_string .= ($key & 1) == 0? 
            mb_ucfirst(strtolower(trim($sentence))) : 
            $sentence.' '; 
    } 
    return trim($new_string); 
}