php replace regular expression

Question

I need to use php to add a space between a period and the next word/letter when there's none.

For example, "This is a sentence.This is the next one." needs to become "This is a sentence. This is the next one." Notice the added space after the first period.

My problem is that even if I'm able to make a regular expression that finds every dot followed by a letter, how do I then replace that dot with a "dot + space" and keep the letter?

Also it needs to keep the case of the letter, lower or upper.

Thanks for your input.

Answer 1

$regex = '#\.(\w)#';
$string = preg_replace($regex, '. \1', $string);

If you want to capture more than just periods, you can do:

preg_replace('#(\.|,|\?|!)(\w)#', '\1 \2', $string);

Simply add the characters you want replaced into the first () block. Don't forget to escape special characters (http://us.php.net/manual/en/regexp.reference.meta.php)