I'm having trouble to find the exact formula to split the string on space if the word is longer than 2 character.

$str = 'test 1 vitamin d3 test 2';

$str_parts = preg_split('#(?:\s |(vitamin [cde]))#', $str, -1, PREG_SPLIT_NO_EMPTY|PREG_SPLIT_DELIM_CAPTURE);

var_export($str_parts);

An ideal output would be:

['test 1', 'vitamin d3', 'test 2']

CodePudding user response：

You may use this regex in split:

\h (?=\w{3})

Which matches 1 whitespaces if there is a word with at least 3 characters afterwards using a positive lookahead.

RegEx Demo

Code:

$str = 'test 1 vitamin d3 test 2';
$str_parts = preg_split('/\h (?=\w{3})/', $str);
print_r($str_parts);

Output:

Array
(
    [0] => test 1
    [1] => vitamin d3
    [2] => test 2
)

CodePudding user response：

You can use a reverse logic and extract sequences of a 3 or more letter word followed with 1-2 letter words:

preg_match_all('~\b\w{3,}(?:\W \w{1,2})*\b~', $text, $matches)

See the regex demo. Details:

• \b - a word boundary
• \w{3,} - three or more word chars
• (?:\W \w{1,2})* - zero or more occurrences of
  • \W - one or more non-word chars
  • \w{1,2} - one to two word chars
• \b - a word boundary