Beefy Boxes and Bandwidth Generously Provided by pair Networks
No such thing as a small change
 
PerlMonks  

How do I substitute case insensitively on the LHS, but preserving case on the RHS?

by faq_monk (Initiate)
on Oct 08, 1999 at 00:25 UTC ( #660=perlfaq nodetype: print w/ replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

It depends on what you mean by ``preserving case''. The following script makes the substitution have the same case, letter by letter, as the original. If the substitution has more characters than the string being substituted, the case of the last character is used for the rest of the substitution.

    # Original by Nathan Torkington, massaged by Jeffrey Friedl
    #
    sub preserve_case($$)
    {
        my ($old, $new) = @_;
        my ($state) = 0; # 0 = no change; 1 = lc; 2 = uc
        my ($i, $oldlen, $newlen, $c) = (0, length($old), length($new));
        my ($len) = $oldlen < $newlen ? $oldlen : $newlen;

        for ($i = 0; $i < $len; $i++) {
            if ($c = substr($old, $i, 1), $c =~ /[\W\d_]/) {
                $state = 0;
            } elsif (lc $c eq $c) {
                substr($new, $i, 1) = lc(substr($new, $i, 1));
                $state = 1;
            } else {
                substr($new, $i, 1) = uc(substr($new, $i, 1));
                $state = 2;
            }
        }
        # finish up with any remaining new (for when new is longer than old)
        if ($newlen > $oldlen) {
            if ($state == 1) {
                substr($new, $oldlen) = lc(substr($new, $oldlen));
            } elsif ($state == 2) {
                substr($new, $oldlen) = uc(substr($new, $oldlen));
            }
        }
        return $new;
    }

    $a = "this is a TEsT case";
    $a =~ s/(test)/preserve_case($1, "success")/gie;
    print "$a\n";

This prints:

    this is a SUcCESS case

Log In?
Username:
Password:

What's my password?
Create A New User
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others wandering the Monastery: (8)
As of 2014-12-29 17:07 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    Is guessing a good strategy for surviving in the IT business?





    Results (194 votes), past polls