<?php
 
error_reporting(-1);
mb_internal_encoding('utf-8');
 
$text = "ну что.      не смотрел еще black mesa.я собирался скачать  ,но все как-то некогда было.";
// Для тестов
$text1 = "roses are red,and violets are blue.whatever you do i'll keep it for you.";
$text2 = 'привет.есть 2 функции,preg_split и explode ,не понимаю,в чем между ними разница.';
function makeFirstLetterUppercase($text) {
    $sent = preg_split("/\\./", $text, 0, PREG_SPLIT_NO_EMPTY);
    foreach ($sent as $number => $sentence) {
    	if (mb_substr(0, 1, $sentence) != " ") {
    		$sentence = " ". $sentence;
    	}
    	var_dump($sentence);
    	$newSentence = preg_replace("/\\s?([,!?])\\s?/u", '$1 ', $sentence); //знаки препинания
    	var_dump($newSentence);
    	$newSentence = preg_replace("/\\s{2,}/u", ' ', $sentence); //повторяющийся пробел
    	$firstLeter = mb_strtoupper(mb_substr($newSentence, 1,1));
    	$newSentence = preg_replace("/^ (\\w)/u", " {$firstLeter}", $newSentence);
    	$newText = $newText . $newSentence. ".";
    }
    return $newText;
}
$newText = makeFirstLetterUppercase($text);
echo "{$newText}\n";
$newText = makeFirstLetterUppercase($text1);
echo "{$newText}\n";
$newText = makeFirstLetterUppercase($text2);
echo "{$newText}\n";

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