I would like to create a way of matching strings like abc(xyz) abc abc(xyz)[123] where each bracket is an optional unit. What I would like to have, optimally, is something like preg_match_all('complicated regex', $mystring, $matches); with $matches returning the following: If $mystring= abc(xyz)[123]R gives $matches=array(0 => "abc", 1=> "xyz", 2=> "123", 3=> "R") If $mystring= abc(xyz)R gives $matches=array(0 => "abc", 1=> "xyz", 2=> "", 3=> "R") If $mystring= abc[123]R gives $matches=array(0 => "abc", 1=> "", 2=> "123", 3=> "R") If $mystring= abc(xyz)[123] gives $matches=array(0 => "abc", 1=> "xyz", 2=> "123", 3=> "") If $mystring= abc gives $matches=array(0 => "abc", 1=> "", 2=> "", 3=> "") I hope you get the point. I tried as follows: preg_match_all("/([a-z]*)($[a-zA-Z]$)?(\[\w\])?/", "foo(dd)[sdfgh]", $matches) for which matches[0] is Array ( [0] => foo [1] => [2] => dd [3] => [4] => [5] => sdfgh [6] => [7] => ) why do I get the additional empty matches? How to avoid them to have results as I need to (either in matches or in matches[0] ...).

Reputation: 44305

Regular expression in php with preg_match_all

I would like to create a way of matching strings like

abc(xyz)
abc
abc(xyz)[123]

where each bracket is an optional unit. What I would like to have, optimally, is something like

preg_match_all('complicated regex', $mystring, $matches);

with $matches returning the following:

If $mystring= abc(xyz)[123]R gives $matches=array(0 => "abc", 1=> "xyz", 2=> "123", 3=> "R")
If $mystring= abc(xyz)R gives $matches=array(0 => "abc", 1=> "xyz", 2=> "", 3=> "R")
If $mystring= abc[123]R gives $matches=array(0 => "abc", 1=> "", 2=> "123", 3=> "R")
If $mystring= abc(xyz)[123] gives $matches=array(0 => "abc", 1=> "xyz", 2=> "123", 3=> "")
If $mystring= abc gives $matches=array(0 => "abc", 1=> "", 2=> "", 3=> "")

I hope you get the point. I tried as follows:

preg_match_all("/([a-z]*)(\([a-zA-Z]\))?(\[\w\])?/", "foo(dd)[sdfgh]", $matches)

for which matches[0] is

Array
(
    [0] => foo
    [1] => 
    [2] => dd
    [3] => 
    [4] => 
    [5] => sdfgh
    [6] => 
    [7] => 
)

why do I get the additional empty matches? How to avoid them to have results as I need to (either in matches or in matches[0]...).

Upvotes: 5

Answers (6)

hegemon

Reputation: 6764

You get so many results because your match starts on and on again 8 times. All The string (including empty strings) are matched against the first, non-optinal part of the regex: ([a-z]*).

The corrected regex:

preg_match_all("/^([a-z]*)(\([a-zA-Z]*\))?(\[\w*\])?$/", "foo(ddd)[sdfgh]", $matches);

EDIT (to exclude brackets in the second part of the subject) So we want 'ddd' instead of '(ddd)':

This regex uses a "non capturing pattern" (?: ... ) in order to mark an optional part of the subject, but not to capture it in the matches array.

preg_match_all("/^([a-z]*)(?:\(([a-zA-Z]*)\))?(\[\w*\])?$/", "foo(ddd)[sdfgh]", $matches);

The interesting part is this: (?:$([a-zA-Z]*)$)?.

first paren (?: marks the beginning of a non capturing subpattern
second paren \( is an escaped literal paren
third one ( mark the beginning of standard capturing subpattern

Only contents of the third parens pair will show up in the $matches array.

Upvotes: 1

Ja͢ck

Reputation: 173542

The optional last letter throws off the results a bit, but this expression will cover it:

function doit($s)
{
        echo "==== $s ====\n";
        preg_match_all('/(\w+) # first word
                (?: \(([^)]+)\) )? # match optional (xyz)
                (?: \[([^]]+)\])? # match optional [123]
                (\w?) # match optional last char
                /x', $s, $matches, PREG_SET_ORDER);

        print_r($matches);
}

doit('abc(xyz)[123]R xyz(123)');
doit('abc(xyz)R');
doit('abc[123]R');
doit('abc(xyz)[123]');

Results

==== abc(xyz)[123]R xyz(123) ====
Array
(
    [0] => Array
        (
            [0] => abc(xyz)[123]R
            [1] => abc
            [2] => xyz
            [3] => 123
            [4] => R
        )

    [1] => Array
        (
            [0] => xyz(123)
            [1] => xyz
            [2] => 123
            [3] => 
            [4] => 
        )

)
==== abc(xyz)R ====
Array
(
    [0] => Array
        (
            [0] => abc(xyz)R
            [1] => abc
            [2] => xyz
            [3] => 
            [4] => R
        )

)
==== abc[123]R ====
Array
(
    [0] => Array
        (
            [0] => abc[123]R
            [1] => abc
            [2] => 
            [3] => 123
            [4] => R
        )

)
==== abc(xyz)[123] ====
Array
(
    [0] => Array
        (
            [0] => abc(xyz)[123]
            [1] => abc
            [2] => xyz
            [3] => 123
            [4] => 
        )

)

Upvotes: 0

Toto

Reputation: 91385

how about:

/^(\w*)(?:\((\w*)\))?(?:\[(\w*)\])(\w*)?$/

usage:

preg_match_all("/^(\w*)(?:\((\w*)\))?(?:\[(\w*)\])(\w*)?$/", "abc[123]R", $matches); 
print_r($matches);

output:

Array
(
    [0] => Array
        (
            [0] => abc[123]R
        )

    [1] => Array
        (
            [0] => abc
        )

    [2] => Array
        (
            [0] => 
        )

    [3] => Array
        (
            [0] => 123
        )

    [4] => Array
        (
            [0] => R
        )

)

explanation:

The regular expression:

(?-imsx:^(\w*)(?:\((\w*)\))?(?:\[(\w*)\])(\w*)?$)

matches as follows:

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    \w*                      word characters (a-z, A-Z, 0-9, _) (0 or
                             more times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  (?:                      group, but do not capture (optional
                           (matching the most amount possible)):
----------------------------------------------------------------------
    \(                       '('
----------------------------------------------------------------------
    (                        group and capture to \2:
----------------------------------------------------------------------
      \w*                      word characters (a-z, A-Z, 0-9, _) (0
                               or more times (matching the most
                               amount possible))
----------------------------------------------------------------------
    )                        end of \2
----------------------------------------------------------------------
    \)                       ')'
----------------------------------------------------------------------
  )?                       end of grouping
----------------------------------------------------------------------
  (?:                      group, but do not capture:
----------------------------------------------------------------------
    \[                       '['
----------------------------------------------------------------------
    (                        group and capture to \3:
----------------------------------------------------------------------
      \w*                      word characters (a-z, A-Z, 0-9, _) (0
                               or more times (matching the most
                               amount possible))
----------------------------------------------------------------------
    )                        end of \3
----------------------------------------------------------------------
    \]                       ']'
----------------------------------------------------------------------
  )                        end of grouping
----------------------------------------------------------------------
  (                        group and capture to \4 (optional
                           (matching the most amount possible)):
----------------------------------------------------------------------
    \w*                      word characters (a-z, A-Z, 0-9, _) (0 or
                             more times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )?                       end of \4 (NOTE: because you are using a
                           quantifier on this capture, only the LAST
                           repetition of the captured pattern will be
                           stored in \4)
----------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------

Upvotes: 1

HamZa

Reputation: 14921

And why don't you use preg_split() ?

$string = 'abc(xyz)[123]';
$array = preg_split('/\]?\(|\)\[?|\[|\]/', $string);
print_r($array);

Online Demo

Upvotes: 0

Casimir et Hippolyte

Reputation: 89547

A way to obtain what you need without empty items:

$pattern = '~(?|\[(\w*+)]|\(([a-zA-Z]*+)\)|\b([a-z]*+)\b)~';
preg_match_all($pattern, 'foo(dd)[sdfgh]', $matches);
print_r($matches[1]);

Notice : this can match empty strings in brackets, to avoid them, replace * by +

Upvotes: 0

Harry Dobrev

Reputation: 7706

Try using this simple regex:

[a-zA-Z0-9]+

When using preg_match_all it will find all substrings which match the given pattern and separate them in groups if there are braces, brackets or other characters between them.

preg_match_all("/[a-zA-Z0-9]+/", "foo(dd)[sdfgh]", $matches);
print_r($matches);

Array
(
    [0] => Array
        (
            [0] => foo
            [1] => dd
            [2] => sdfgh
        )

)

If for some reason you need to have the braces and brackets separately you could use grouping like this:

([\(\)\[\]])?([a-zA-Z0-9]+)([\(\)\[\]])?

preg_match_all("/([\(\)\[\]])?([a-zA-Z0-9]+)([\(\)\[\]])?/", "foo(dd)[sdfgh]", $matches); 
print_r($matches);

Array
(
    [0] => Array
        (
            [0] => foo(
            [1] => dd)
            [2] => [sdfgh]
        )

    [1] => Array
        (
            [0] => 
            [1] => 
            [2] => [
        )

    [2] => Array
        (
            [0] => foo
            [1] => dd
            [2] => sdfgh
        )

    [3] => Array
        (
            [0] => (
            [1] => )
            [2] => ]
        )

)

Upvotes: 0

Regular expression in php with preg_match_all

Answers (6)

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