use strict;
use warnings;

use IO::File;

my $inFile = q{spw623147.txt};

my $inFH = IO::File->new($inFile, O_RDONLY)
#open my $inFH, q{<}, $inFile
   or die qq{open: $inFile: $!\n};

while ( $_ = $inFH->getline() )
#while ( <$inFH> )
{
    if ( m{\A\.rem} )
    {
        print qq{  Comment Line: $_};
        next;
    }
    if ( m{\A\.declare\s+(\S+)} )
    {
        print qq{     Data Line: $_};
        print qq{   Variable is: $1\n};
        next;
    }
    print qq{Not recognised: $_};
}

$inFH->close()
#close $inFH
   or die qq{close: $inFile: $!\n};
[download]

Cheers,

JohnGG

Per the documentation of IO::File, you call the open() method on the IO::File object instead of using open directly. Which part of that is giving you trouble? What output do you receive?

Hi John, Thanx for the solution ... Please tell me how to use IO::File module instead of open function in this scenario.

Actually, it's the other way round: you are using IO::File (BTW: to render this link in the source of your node you can use [mod://IO::File]) and he suggested you to use a plain regular open. If you actually read (did you?) his post, you'll notice he gives you and explicit example about how to do so, namely:

my $inFile = q{spw623147.txt};
open my $inFH, q{<}, $inFile
   or die qq{open: $inFile: $!\n};
[download]

So, what's wrong with that?!?

BTW: if you are confused by the alternate delimiters, the use of which in this context may be exaggerate and controversial to some, that can be:

my $inFile = 'spw623147.txt';
open my $inFH, '<', $inFile or die "open: $inFile: $!\n";
[download]