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

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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Re: Re: Re: Re: Re: Passing an array to a subroutine
by chromatic (Archbishop) on Aug 01, 2001 at 00:06 UTC
    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.

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      Ok - in the spirit of letting perl help me, how does open handle arrays that are not explicitly files? In my code, $data is just what I read in from @_, not a file. But when I run this (even in the debugger) all the contents of $data are written to STDOUT and the program terminates (not the desired output!). Update: I did what you suggested, and get the following error: 
      ): File name too long at ocean_return2b.pl line 176, <STDIN> line 4.
Debugged program terminated.  Use q to quit or R to restart,

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      line 176: open(FILE, $aref) or die "Cannot open: ($aref): $!"; It seems that it tries to open the entire contents of $aref, as that is what is returned to the screen.
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