string - Explode a paragraph into sentences in PHP

Question

I have been using

explode(".",$mystring)

to split a paragraph into sentences. However this doen't cover sentences that have been concluded with different punctuation such as ! ? : ;

Is there a way of using an array as a delimiter instead of a single character? Alternativly is there another neat way of splitting using various punctuation?

I tried

explode(("." || "?" || "!"),$mystring)

hopefully but it didn't work...

Answer 1

You can use preg_split() combined with a PCRE lookahead condition to split the string after each occurance of ., ;, :, ?, !, .. while keeping the actual punctuation intact:

Code:

$subject = 'abc sdfs.    def ghi; this is an.email@addre.ss! asdasdasd? abc xyz';
// split on whitespace between sentences preceded by a punctuation mark
$result = preg_split('/(?<=[.?!;:])s+/', $subject, -1, PREG_SPLIT_NO_EMPTY);
print_r($result);

Result:

Array
(
    [0] => abc sdfs.
    [1] => def ghi;
    [2] => this is an.email@addre.ss!
    [3] => asdasdasd?
    [4] => abc xyz
)

You can also add a blacklist for abbreviations (Mr., Mrs., Dr., ..) that should not be split into own sentences by inserting a negative lookbehind assertion:

$subject = 'abc sdfs.   Dr. Foo said he is not a sentence; asdasdasd? abc xyz';
// split on whitespace between sentences preceded by a punctuation mark
$result = preg_split('/(?<!Mr.|Mrs.|Dr.)(?<=[.?!;:])s+/', $subject, -1, PREG_SPLIT_NO_EMPTY);
print_r($result);

Result:

Array
(
    [0] => abc sdfs.
    [1] => Dr. Foo said he is not a sentence;
    [2] => asdasdasd?
    [3] => abc xyz
)