On Mar 4, Sethi, Pradeep said:
>I have a number 342389842452.
>
>how do a substitute of everything with X but last 4 digits using regular
>expressions
>
>like xxxxxxxx2452
You could take an approach like:
s/\d(?=\d{4})/x/g;
The (?=...) means "look ahead for ...". So this regex matches a digit,
and then checks to see if it CAN match four more digits, without really
going there in the string. If it matches, it replaces the digit with an
"x".
A much simpler approach to understand is:
s/(\d+)(\d{4})/"x" x length($1) . $2/e;
This time, we match all the digits we can to $1, allowing us to back up a
little to match four digits into $2. Then we replace ALL of that with
length($1) x's, followed by the four digits saved in $2. The /e modifier
means that the replacement is code to be executed.
--
Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/
** Look for "Regular Expressions in Perl" published by Manning, in 2002 **
<stu> what does y/// stand for? <tenderpuss> why, yansliterate of course.
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