Re: Opening file($ARGV) with Getopt - failing

[John W. Krahn]

Edward Wijaya wrote:
> Hi,
Hello,
> Why my code below fail to open and
> print the file contents
>
> when I do:
>
> perl mycode.pl -f filename
>
>
> __BEGIN__
> use strict;
> use warnings;
>
> use Getopt::Std;
> use vars qw($f);
> getopts('f:');
getopts( 'f:' ) creates the variable $opt_f and stores the following argument 
'filename' in that variable and *REMOVES* those arguments from @ARGV so that 
@ARGV is now empty.

> my    $f = $ARGV[0];
Since @ARGV is now empty, $f is also empty (undef).
> open ( INFILE, '<', $f)
>     or die "$0 : failed to open input file $f : $!\n";
> close ( INFILE );
>
> while ( <> )
Since @ARGV is now empty there is nothing for <> to open and read from.
> {
>     print $_;
> }   __END__
You should do it like this instead:
use strict;
use warnings;
use Getopt::Std;
getopts( 'f:', \my %opt );
open INFILE, '<', $opt{ f } or die "$0 : failed to open input file $opt{f} : $!";
while ( <INFILE> ) {
    print;
}
close INFILE;
__END__

John
--
use Perl;
program
fulfillment
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