I was messing around with some stuff today and noticed something that seemed odd to me but is probably known by most. I noticed that in the following code no print statements were printed to stdout until the script was completely done.

#!perl -w

use strict;
my $count = 0;
my $times = 0;
my $sec   = 0;

print "Doing something ";
while (1) {
   my $time = localtime();
   my @broken = split(/ /, $time);
   for (@broken) {
      $time = $1 if (/((\d+)\:(\d+)\:(\d+))/);
   }
   my @stime = split(/\:/, $time);
   if ($sec < $stime[2]) {
      $count++;
   }
   $sec = $stime[2];
   
   if ($count == 5) {
      print ". ";
      $count = 0;
      $times++;
   }
   last if ($times == 12);
}
print " done!\n";
[download]

Now if I added a print statement anywhere in there with a newline character it printed as it went along like it is suppose to.

#!perl -w

use strict;
my $count = 0;
my $times = 0;
my $sec   = 0;

print "Doing something ";
while (1) {
   my $time = localtime();
   my @broken = split(/ /, $time);
   for (@broken) {
      $time = $1 if (/((\d+)\:(\d+)\:(\d+))/);
   }
   my @stime = split(/\:/, $time);
   if ($sec < $stime[2]) {
      $count++;
      print "Incremented count!\n";
   }
   $sec = $stime[2];
   
   if ($count == 5) {
      print ". ";
      $count = 0;
      $times++;
   }
   last if ($times == 12);
}
print " done!\n";
[download]

Any explanation of this behavior?

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