in reply to Writing to same line in STDOUT

Nice try! Instead, try printing "\r" to bring the cursor back to the beginning of the line. That way you can overwrite the same line to your heart's content.

#! /usr/bin/perl

use strict;

my $in = shift || '/usr/dict/words';
open IN, $in or die "Cannot open $in for input: $!\n";
while( <IN> ) {
        chomp;
        print "$_\r";
}
close IN;
print "\n";

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Re: Re: Writing to same line in STDOUT
by mugwumpjism (Hermit) on Jun 14, 2001 at 14:35 UTC

    ...but you'd better make sure that you're actually writing to a terminal:

    #!/usr/bin/perl

use strict;

my $in = shift || '/usr/share/dict/words';
my $running_on_terminal = -t STDOUT;
my $last_word_length;

open IN, $in or die "Cannot open $in for input: $!\n";

while( <IN> ) {
    chomp;
    if ($running_on_terminal) {
         my $length_diff = $last_word_length - length($_);
        $length_diff >= 0
            or $length_diff = 0;
        print ("\rProcessing $_..." . (" " x $length_diff)
               . ("\b" x $length_diff));
        $last_word_length = length($_);
    }

    # do something with $_
}
print "\n" if ($running_on_terminal);

close IN;

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    caveat: this code still assumes the user's terminal is wide enough for any line we're going to print.

    You might want to wrap it up into a module or object, so you can go:

    my $pm = new ProgressMeter(-items => scalar @list);

$pm->start;
my $c;
for my $item (@list) {
    $pm->update(++$c);
}
$pm->finish;

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    I wrote something like that once, but unfortunately it is owned by the company I wrote it for :-(

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