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preg_match_all: Test if match is at beginning of sentance

hankknight asked
Last Modified: 2010-05-18
The regex I use allows false positives for some one-word sentaces contain only one word with three letters or less.

Only the following should be returned:

array(1) {
  array(8) {
    string(10) "Mrs. Smith"
    string(16) "Dr. Strangelove "
    string(6) "London"
    string(10) "Mr. Jones "
    string(6) "London"

set_time_limit (0);
$fulltext = ". This is a test for Mrs. Smith. I am Dr. Strangelove and I am just testing this! Yes. It should work, but does it? Bad. Test it for yourself and see. Now. Do you live in London? No? , as often led Mr. Jones to London.";
	$find = array('&ldquo;', '&rdquo;', '&rsquo;', '&lsquo;', '&ndash;', '&#39;', '&#38;', '&amp;');
	$fulltext = preg_replace('/\s+/',' ', strip_tags(". " .   str_ireplace($find, ' ' , $fulltext)));
	// Thanks, ddrudik and ozo
	$pattProper='/[A-Z][a-z]{1,2}\.\s+(?:[A-Z][a-z]+\s*)*|(?<![.?!] )(?<!;)(?:[A-Z][a-z]+\s*)+/';
	preg_match_all($pattProper, $fulltext, $proporNouns);

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Thanks for the question and the points.
Top Expert 2008

OK, Why shouldn't there be "This", No" and "Yes" be found?
They are nouns too or is there any special rule to apply to this task?

Could you please explain why f.ex. London should be included in the outupt? If it's because it's right before a '?', so why should then "No?" not be found by the regex?

Proper nouns was the issue.
Top Expert 2008

Oh, ok, that explains it.

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