Using variables for File Handles

[erdman]

Is it possible to use a variable for a file handle.

EX.
sub printReport($handle,@array,$arraySize){
for ($i=0;$i<$arraySize;$i++){
print ($handle "$array[$i]\n");
}#end for
}#end sub printReport

 

[dmazzini]

Here an example. Cheers


$file =$ARGV[0];
$/=undef;
open FH, "<$file";
$perlcode=<FH>;
close FH;
$perlcode=~ s/\r//g;
open FH, ">$file";
print FH "$perlcode";
close FH;



dmazzini
GSM System and Telecomm Consultant

 

[KevinADC]

Why would you want to use a variable file handle? There should be no need to. This is also not correct syntax:

sub printReport($handle,@array,$arraySize){

that's not the way to import arguments to your sub routine, it should be:

sub printReport {
   my ($handle,$arraySize,@array) = @_;
   ....
}

note that the array should be the last argument if you don't use references and there is more than one argument.

 

[mikevh]

dmazzini, I don't see where you're using a variable as a file handle?

erdman, you can do it like this.

#!perl
use strict;
use warnings;

my $HANDLE;
open($HANDLE, ">erdman.txt") || die qq(Can't open "erdman.txt"!\n);
my @array = qw(apples oranges peaches pears grapes);
printReport($HANDLE, @array);
close($HANDLE) || die qq(Can't close "erdman.txt"!\n);

[b]sub printReport {
    my ($HANDLE, @array) = @_;
    for (my $i=0;$i<@array;$i++){
        print ($HANDLE "$array[$i]\n");[/b]
    }#end for
}#end sub printReport

Note that the header of your subroutine is not valid Perl. Also the parameter arraySize is not necessary. And if you pass an array or hash to a sub, it must be the last argument. (You can get around this by using references.)

HTH

 

[dmazzini]

Yes you are right,

I am assigning the content of the filehandle to the variable.... $perlcode=<FH>;

I need to wake up! Thanks


dmazzini
GSM System and Telecomm Consultant

 

[KevinADC]

Just curious:

What is the purpose of using a variable for a filehandle? Why would it be necessary?

 

[erdman]

I am writing out a couple of files that are utilizing the same output structure. In order to save lines of code I have created a subroutine to perform the action. After I asked the question I went to my books and found what was needed. The files change sizes due to removal of duplicates.

&printDistinct("DISTINCT",$distGroups,0,@scratch);

sub printDistinct(){
($handle,$size,$start,@array)=@_;
for ($i=$start;$i<$size;$i++){
print ($handle "$array[$i]\n");
}#end for
}#end sub printReport

 

[chazoid]

In some cases you might want to store filehandles in an array or other type of data structure:

open (LOG1,">",$logfile1);
open (LOG2,">",$logfile2);

@logfh = (*LOG1, *LOG2);

print $_ "hello" for @logfh;

It's actually a good idea to always use lexical scalars for filehandles - of course you should always close your filehandles, but in the following example it will be closed when it goes out of scope.

{ 
open (my $fh,">",$file);
print $fh "hello";
}