Need Help In Regex, substring between two regex

Question

Please read part 1 of this question:-

Need Help In Regex, substring between two brackets

$result = '';
$str = ' ... [ ... SUB_STRING_TO_BE_SEARCHED ... ] ... [ ... / ... SUB_STRING_TO_BE_SEARCHED ... ] ... [ ... THIS_SHOULD_NOT_GET_SELECTED ... ]';
$sub_str = '';
if( preg_match('#\[.*?'.$sub_str.'.*?\]#' , $str) ) {
    if ( preg_match( REGEX_2 , $str ) ) {
        $result = preg_replace( REGEX_3 , '', $str);
    } else {
        $result = preg_replace('#\[.*?'.$sub_str.'.*?\]#', '', $str);
    }
}

$result should be:-

$result = " ...  ... [ ... THIS_SHOULD_NOT_GET_SELECTED ... ]";

However, for $str_2:-

$str_2 = ' ... [ ... SUB_STRING_TO_BE_SEARCHED ... ] ... [ ... THIS_SHOULD_NOT_GET_SELECTED ... ]';

the $result should also remain:-

$result = " ...  ... [ ... THIS_SHOULD_NOT_GET_SELECTED ... ]";

Explanation:-

Step 1: Ok, from previous question I can easily get this string:-

[ ... THIS_SHOULD_NOT_GET_SELECTED ... ]

Step 2:- REGEX_2 should check if this exists:-

[ ... / ... THIS_SHOULD_NOT_GET_SELECTED ... ]

(notice a forward slash, let's assume that it will appear only once between the THIS_SHOULD_NOT_GET_SELECTED and the left bracket [.)

Step 3:- If REGEX_2 is found then REGEX_3 should select this substring:-

[ ... SUB_STRING_TO_BE_SEARCHED ... ] ... [ ... / ... SUB_STRING_TO_BE_SEARCHED ... ]

Another Examples:-

$str_3 = ' ... [ ... AA ... ] ... [ ... / ... AA ... ] ... [ ... B ... ] ... [ ... AA ... ] ... [ ... / ... AA ... ] ... [ ... AA ... ]';
$substring_3 = 'AA'
$result = ' ...  ... [ ... B ... ] ...  ... ';

Jerry · Accepted Answer · 2014-04-01 10:21:07Z

2

I would opt for negated classes instead of .*?, and in case the substring_3 is AA, then:

\[[^]]*?AA[^]]*?\](?:[^[]*\[[^]]*?/[^]]*?AA[^]]*?\])?

In:

$result = preg_replace('#\[[^]]*?'.$sub_str.'[^]]*?\](?:[^[]*\[[^]]*?/[^]]*?'.$sub_str.'[^]]*?\])?#', '', $str);

regex101 demo

\[          # Match [
  [^]]*?    # Any number of non ]
  AA        # The substr
  [^]]*?    # Any number of non ]
\]          # Match ]
(?:
  [^[]*     # Any number of non [
  \[        # Match [
    [^]]*?  # Any number of non ]
    /       # Match /
    [^]]*?  # Any number of non ]
    AA      # The substr
    [^]]*?  # Any number of non ]
  \]        # Match ]
)?          # Make this group optional

edited Apr 1, 2014 at 10:21

answered Apr 1, 2014 at 10:13

Jerry

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1 Comment

Jerry Over a year ago

@OmarTariq Well, if you find something like that beautiful... :)

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