PHP preg_split (with the delimiter included)

Question

I was trying to include the delimiter while using preg_split but was unsuccessful.

print_r(preg_split('/((?:fy)[.]+)/', 'fy13 eps fy14 rev', -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY));

I'm trying to return:

array(
    [0] => fy13 eps
    [1] => fy14 rev
)

With the flags parameter set to PREG_SPLIT_DELIM_CAPTURE:

If this flag is set, parenthesized expression in the delimiter pattern will be captured and returned as well.

The fy is in parenthesis, so I don't know why this doesn't work.

Andrew Clark · Accepted Answer · 2013-06-13 20:34:28Z

6

Your current approach isn't working because "parenthesized expression" here is referring to capturing groups, and the ?: to start your group makes it a non-capturing group. So you can get the fy included by changing your expression to /(fy)/, however I don't think this is what you want because you will get an array that contains fy, 13 eps, fy, and 14 eps (the parenthesized expressions are separate entries in the result).

Instead, try the following:

print_r(preg_split('/(?=fy)/', 'fy13 eps fy14 rev', -1, PREG_SPLIT_NO_EMPTY));

This uses a lookahead to split just before each occurrence of fy in your string.

answered Jun 13, 2013 at 20:34

Andrew Clark

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Casimir et Hippolyte · Accepted Answer · 2013-06-13 22:03:57Z

0

With the example you gave, I am not sure that you really need to use the preg_split function. For example you can obtain the same with preg_match_all in a more efficient way (from the perspective of performance):

preg_match_all('/fy(?>[^f]++|f++(?!y\d))*/', 'fy13 eps fy14 rev', $results);
print_r($results);

The idea here is to match fy followed by all characters but f one or more times or f not followed by y all zero or more times.

More informations about (?>..) and ++ respectively:

here for atomic groups
and here for possessive quantifiers

edited Jun 13, 2013 at 22:03

answered Jun 13, 2013 at 21:56

Casimir et Hippolyte

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