CODEWITHSUNDEEP
perl
Bijan
Bijan

Reputation: 8602

Perl: Have output update dynamically

I have a variable $i that goes from 1 to 100. Is it possible to have the page display the # dynamically replacing the # that was there before?

Suppose I have the following code:

#!/usr/bin/perl

my $i = 0;

for my $i ('1' .. '10') {
    print "$i";
    sleep(1);
}

How do I make it so instead of print "12345...", it just replaces the # that was there before. So 1 becomes 2, 2 becomes 3, etc

Upvotes: 0

Views: 154

Answers (2)

elcaro
elcaro

Reputation: 2297

"\r" returns the cursor to the beginning of the line. Instead, you probably just want to backspace the last printed number, and print the next one... Something like this:

$| = 1;    
my $i = 0;
while ($i < 10) {
    print $i;
    sleep 1; # REPLACE WITH WHATEVER PROCESS YOU NEED TO DO
    print "\b" x length $i++;
}

The last line of the while loop prints a backspace the same length of the number it just printed, and then increments it. This is because the postfix ++ increments after evaluation.

Upvotes: 2

ikegami
ikegami

Reputation: 385867

For something simple like that, you can just move the cursor back using backspace or carriage return.

$| = 1;  # Autoflush.

for my $i (1..10) {
   print("\r", $i);
   sleep(1);
}

print("\n");

Upvotes: 6

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