Re: reading files from a directory

[toolic]

Get rid of the whitespace surrounding your IN filehandle. Change:

while ( < IN > ){

To:

while ( <IN> ){

B::Deparse can shine a little more light upon the situation (Tip #6 from the Basic debugging checklist):

perl -MO=Deparse 867882.pl

my $dir = 'input_files';
die "can't opendir $!" unless opendir DIR, $dir;
while (defined(my $file = readdir DIR)) {
    do {
        print "The directory and file are $dir/$file\n";
        die "Can't open input file $!" unless open IN, "< $dir/$file";
        use File::Glob ();
        while (defined($_ = glob(' IN '))) {
            print $_;
        }
    };
}
closedir DIR;

Here is an explanation from perlop:

Even <$x > (note the extra space) is treated as glob("$x ") , not readline($x).

[kevyt]

I got it thanks! This will help with something called Indivo. http://wiki.chip.org/indivo/index.php/Schemas

while (defined($_ = glob(' IN '))) {
            print "Hello $_";
        }
        while (<IN>){
          print "Bye " . $_ ;
        }

I need to read about glob because I don't understand that line. Which print statement has better style? Should I use the . (join) in a print? Thanks, Kevin

[kcott]

There's no need to concatenate arguments to print as that function takes a list. In fact, you're actually requesting additional processing: do the concatenation and then do the print. Even worse, if you concatenate multiple arguments you're performing multiple operations; in sort of pseudocode: print A.B.C.D performs A.B, then AB.C, then ABC.D, then print ABCD, while print A,B,C,D is one operation.

As far as style is concerned, I'd say do whatever is easiest to read and maintain. print "X ", $_, "\n"; and print "X $_\n"; are equally valid but, as mentioned above, avoid print "X " . $_ . "\n";.

I note there's a few places where you haven't included a newline (\n) at the end of your print statement. In case you didn't know, print doesn't automatically add one for you; say, on the other hand, does.

[kevyt]

Thanks very much. I am not able to print the contents of the file. I'll read about glob and the explanation in the perlop. Thank you!

my $dir = 'input_files';
die "can't opendir $!" unless opendir DIR, $dir;
while (defined(my $file = readdir DIR)) {
    do {
        print "The directory and file are $dir/$file\n";
        die "Can't open input file $!" unless open IN, "< $dir/$file";
        use File::Glob ();
        while (defined($_ = glob(' IN '))) {
            print $_;
        }
    };
}
closedir DIR;

Output

perl create_indivo_schemas.pl
Name "main::IN" used only once: possible typo at create_indivo_schemas
+.pl line 18.
The directory and file are input_files/allergies
INThe directory and file are input_files/immunizations
INThe directory and file are input_files/..
INThe directory and file are input_files/.