Ohh, *if* there is some binary within the tag and *if* the "length" field says sth. about its *length* you could easily construct a regex that extracts binary data of that length: 
 my $binary = pack 'F*', (3.141592) x 10;  # make binary vector of len
+gth 80 bytes
 my $string = '...blah...<file fiop="foo" length="' . length($binary) 
+.'"/>' . $binary . '</file>...blah...';

 my ($fiop, $length, $data)
    = $string =~ m{<file                   # tag anchor
                   \s+ fiop="([^"]+)"      # (fiop)
                   \s+ length="([^"]+)"    # (length)
                   />                      # end: start file tag
                   ((??{ "\\C{$2}" }))     # self modifying regex for 
+binary stuff
                   </file>                 # end: file tag
                  }sx;

 print "$fiop, $length (data comes below)\n";
 print join ',', unpack("F*", $data);      # extract binary data again
 
 (my $notags = $string) =~ s{<file.+</file>}{};
 print "\n$notags\n";

[download]

In the above I pack a binary sequence of 10 Pi-Numbers (double, 10 x 8 bytes) into the tag, match a binary sequence of its length ($2) and unpack it afterwards.

Regards

mwa

In reply to Re^3: extracting a substring from a string - multiple variables by mwah
in thread extracting a substring from a string - multiple variables by walinsky

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