Whenever you want to repeat something a given number of times, use a loop. For example, in this case the function to read n lines from a filehandle could be:

sub read_n_lines
{
    my ($fh, $count) = @_;
    my $buffer;
    $buffer .= $_ for 1 .. $count;
    return $buffer;
}
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Use it something like:

open(my $handle, 'c:/file.log') or die "Can't read file: $!\n";

while(not eof( $handle ))
{
    my $chunk  = read_n_lines( $handle, 100 );
    my $parsed = parse_chunk( $chunk );
    print_parsed( $parsed );
}
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You might need a little more logic in read_n_lines() to check for eof, but if you look at the documentation and play around a little bit, you'll figure it out.