Re: Beginner in perl : Use of uninitialized value

[jimpudar]

Just another tip: there is no need to read all of STDIN into an array; you can iterate over each line as it comes in.

while ( my $line = <STDIN> ) {
    ...
}

The diamond operator <> will do some pretty fancy stuff for you by default. You can for example leave out the explicit STDIN:

while ( my $line = <> ) {
    ...
}

What is really cool about this is that now in addition to working with STDIN you can also pass a list of filenames to your Perl program and it will do the right thing.

See perlop - IO Operators for more details on the diamond operator.

Of course you also don't need to set an explicit loop variable for a program of this size; you can just use $_:

while (<>) {
    ...
}

And at this point, you may want to look into Perl's -n command line option, which will automatically wrap your entire program inside that exact same loop:

bash:~$ perl -nE '...'

[jwkrahn]

Just another tip: there is no need to read all of STDIN into an array; you can iterate over each line as it comes in.

foreach my $line (<STDIN>) {
    ...
}

The problem with that is that the foreach loop will read all lines into a list in memory first.

You need a while loop to iterate over one line at a time:

while ( my $line = <STDIN> ) {
    ...
}

[jimpudar]

Quite right, that's what I get for posting without testing my code :).

I edited my comment to correct this.

[Perl_Programmer1992]

Thank you @jwkrahn and @jimpudar , it's been such a great learning so far , I will definitely keep these things in mind when coding next time.