in reply to Re: Passing an array to a subroutine
in thread Passing an array to a subroutine

Thanks. I changed the code as you suggested, but my output files are empty. I ran this under the debugger with a break at that sub routine. When I type p @_ I get all the values in the array, but then p $aref is empty, and the rest of the routine, while it runs, is running on empty data. Thoughts? 
 
sub subgen {
        my $aref = @_;
    my($cur_segno) = 0;
    my(@sst) = ();
    
        open(FILE, $aref); #or die "Cannot open: $file\n";
    
    my $hdr = <FILE>; #read in the first line 
    chomp $hdr;
    my @colnames = split /, ?/, $hdr; #split the header into an array
    
    open GENFILE, '>genfile.txt';
        open INFOFILE, '>infofile.txt';
    
    my $sst_mean;
    my %fronts;
    
        while (<FILE>) {
<snip>

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Re: Re: Re: Passing an array to a subroutine
by suaveant (Parson) on Jul 31, 2001 at 21:04 UTC
    hmmm keep the () around your my $aref line... 
    my ($aref) = @_;
#or do
my $aref = $_[0];
#or 
my $aref = shift;

    [download]
    shift defaults to shift the first value off @_ if you don't supply an array argument.

                    - Ant

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[d/l]
      Here's the current code. When I run it under the debugger, all is well until I get to the my $hdr line. When I step through this and (in the debugger) type p $hdr, it returns nothing; the same is true when I type p @colnames even though p $data returns the whole data array. I'm new at this, so I don't really understand how the FILEHANDLEs work. Even though this syntax seems correct, it doesn't seem to really open that array. I'm lost. 
      sub subgen {
        my($data) = shift;
    chomp($data);
    my($cur_segno) = 0;
    my(@sst) = ();
    
        open(FILE, $data); # or die "Cannot open: @data\n";
    
    my $hdr = <FILE>; #read in the first line 
    chomp $hdr;
    my @colnames = split /, ?/, $hdr; #split the header into an array

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[reply]
[d/l]
        Why would $hdr be empty? Two possibilities. First, it's a blank line. chomping it will remove the newline, leaving a possibly empty string. The second possibility is that the open failed. Here's a better error line:

        open(FILE, $data) or die "Can't open ($data): $!";

        That gives you the name of the file, surrounded by non-whitespace characters as a sanity check, along with the system error message. You'll have better luck if you let Perl help you.

        Update: If it's not a file, don't open it. open works on files (in the Unix sense). If you have the data you want to munge already in an array or a scalar, use split or a regex to get at it. That's the problem.

[reply]
[d/l]

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