in reply to ascii problem

Sounds like a job for a regular expression: 

#!/usr/bin/perl
my $test = "hello there ass\x08\x08wesome";

print "BEFORE: $test, ", "(length: " . length($test) . ")\n";

while ($test =~ /\x08/) {
  $test =~ s/.\x08//;
}

print "AFTER:  $test, ", "(length: " . length($test) . ")\n";

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On my terminal that prints: 

BEFORE: hello there awesome, (length: 23)
AFTER:  hello there awesome, (length: 19)

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You'd need to use a hex editor (or if you're elite, hexl-mode in Emacs) to confirm that the first string actually had backspaces, but the lengths match my expectations.

The regular expression works by finding any character (.) followed by a backspace (\x08) and replacing them with nothing (i.e. deleting them from the string). This is wrapped up in a loop to repeat the process as long as backspaces are present.

-sam

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Re^2: ascii problem
by davido (Cardinal) on Jun 01, 2006 at 21:00 UTC

    That's good, but somehow I just don't like seeing you needing to test with the m// operator, and then perform a nearly equal match for the substitution. To get away with invoking the regexp engine only one time instead of twice on each loop iteration, you can do this instead: 

    use strict;
use warnings;


my $test = "hello there ass\x08\x08wesome";

print "BEFORE: $test, ", "(length: " . length($test) . ")\n";

while ($test =~ /.\x08/) {
    $test = substr( $test, 0, $-[0] ) . substr( $test, $+[0] );

    #   Note: The preceeding line is the same as:
    #       $test = $` . $';
    #   but avoids using $` and $', side-stepping the global
    #   performance penalty associated with their use.

}

print "AFTER:  $test, ", "(length: " . length($test) . ")\n";

    [download]

    Dave

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[d/l]
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[d/l]

        Bingo!
        It pays to take a fresh look, doesn't it? :)


        Dave

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