How to optimize the following perl code?

Question

In the below code I tried to print every line along with its line number. Is there any other way to optimize the below code using Perl?

#!/usr/bin/perl
use strict;
use warnings;
open my $fh,"<","exercise.csv";
while(<$fh>)
{
   print "$.=====>$_";
}
close $fh;

It depends what you mean by optimize. You can make it more concise by using certain language features. The whole loop can be condensed into print "$.=====>$_" while <$fh>; and you don't have to do the close $fh because it will automatically close the filehandle when $fh goes out of scope. You should include or die $! to catch errors from your open (and in theory also your close, as that could fail, but we've just removed it anyway). But that's really a codereview, which should go on Code Review, not here. — simbabque
– simbabque, Commented Nov 15, 2017 at 13:18
Maybe we can benchmark between the print with variable interpolaton, as in posted question, and print with variable concatenation as in print $. .'====>'.$_; — ulix
– ulix, Commented Nov 15, 2017 at 21:02
If you redirect the output to a file instead of printing to the terminal, it may run faster, especially if it is a large file, since the terminal does not need to render everything.... perl my_script.pl > output — xxfelixxx
– xxfelixxx, Commented Nov 16, 2017 at 7:56
What exactly is the problem? Is your program running too slowly? Is it taking up too much memory? — Borodin
– Borodin, Commented Nov 23, 2017 at 13:23

Sobrique · Accepted Answer · 2017-11-15 12:52:25Z

3

No.

When you're optimising, you look at things that are less efficient ways of accomplishing the goal. That's often algorithmic, and looking at where looping is occurring is a good start.

But then there's resource usage optimisation - disk IO is often the most expensive operation - but you need to do all the IO that you're doing, and you're not doing any redundant IO.

And sometimes - system calls or 'shelling out' to other binaries (via system or backticks) can incur overhead. But you don't do that either.

Basically - your code is just not complicated enough to have any significant inefficiencies.

answered Nov 15, 2017 at 12:52

Sobrique

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