<?php
 
error_reporting(-1);
mb_internal_encoding('utf-8');
 
$text1 = "ну что.      не смотрел еще black mesa.я собирался скачать  ,но все как-то некогда было.";
$text2 = "roses are red,and violets are blue.whatever you do i'll keep it for you.";
$text3 = "привет.есть 2 функции,preg_split и explode ,не понимаю,в чем между ними разница.";
 
function fixText($text) {
	$text1 = preg_replace("!(\ )+!iu", " ", $text);
	$text2 = preg_replace("!(\ )?\,(\ )?!iu", ", ", $text1);
	$text3 = preg_replace("!(\ )?\.(\ )?!iu", ". ", $text2);
	$text4 = explode (". ", $text3);
		foreach ($text4 as $key => $sentence) {
			$firstLetterUpper =  ucfirst($sentence);
			$text4 = str_replace($sentence, $firstLetterUpper, $text4);
		}
	$result = implode(". ", $text4);
	return $result;
}
 
$result1 = fixText($text1);
echo "$result1\n";
$result2 = fixText($text2);
echo "$result2\n";
$result3 = fixText($text3);
echo "$result3\n";

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