File handle array

Question

I wanted to choose what data to put into which file depending on the index. However, I seem to be stuck with the following.

I have created the files using an array of file handles:

my @file_h;
my $file;
foreach $file (0..11)
{
    $file_h[$file]= new IT::File ">seq.$file.fastq";
}

$file= index;
print $file_h[$file] "$record_r1[0]$record_r1[1]$record_r1[2]$record_r1[3]\n";

However, I get an error for some reason in the last line. Help anyone....?

This is an oddity of Perl's syntax, since filehandles weren't originally even variables, much less more complicated lvalues. — Mark Reed
– Mark Reed, Commented Jun 3, 2012 at 2:26
What is the error? Also, could you contrive a complete, self contained example? (That would answer some immediate questions like, do you really mean IT::File [sic]? Do you mean index() or $index?) — pilcrow
– pilcrow, Commented Jun 3, 2012 at 21:18

tchrist · Accepted Answer · 2012-06-03 14:23:53Z

20

That should simply be:

my @file_h;
for my $file (0..11) {
    open($file_h[$file], ">", "seq.$file.fastq")
       || die "cannot open seq.$file.fastq: $!";
}

# then later load up $some_index and then print 
print { $file_h[$some_index] } @record_r1[0..3], "\n";

edited Jun 3, 2012 at 14:23

answered Jun 3, 2012 at 4:47

tchrist

80.7k31 gold badges135 silver badges186 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

soger Over a year ago

Interestingly flock $file_h[$some_index],LOCK_EX works without brackets. Does anyone know why? What is exactly a filehandle in perl?

Mark Reed · Accepted Answer · 2012-06-03 02:17:53Z

5

You can always use the object-oriented syntax:

$file_h[$file]->print("$record_r1[0]$record_r1[1]$record_r1[2]$record_r1[3]\n");

Also, you can print out the array more simply:

$file_h[$file]->print(@record_r1[0..3],"\n");

Or like this, if those four elements are actually the whole thing:

$file_h[$file]->print("@record_r1\n");

answered Jun 3, 2012 at 2:17

Mark Reed

96k17 gold badges149 silver badges189 bronze badges

Comments

mjhennig · Accepted Answer · 2012-06-03 01:47:35Z

1

Try assigning the $file_h[$file] to a temporary variable first:

my @file_h;
my $file;
my $current_file;

foreach $file (0..11)
{
    $file_h[$file]= new IT::File ">seq.$file.fastq";
}

$file= index;
$current_file = $file_h[$file];

print $current_file "$record_r1[0]$record_r1[1]$record_r1[2]$record_r1[3]\n";

As far as I remember, Perl doesn't recognize it as an output handle otherwise, complaining about invalid syntax.

answered Jun 3, 2012 at 1:47

mjhennig

6811 gold badge5 silver badges11 bronze badges

Collectives™ on Stack Overflow

File handle array

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related