The defined function is what you need. It returns true if the value being tested IS NOT the special undef value. So something like:

unless (defined($line_split[0])) {...} ...
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ahead of your other tests should get the job done.

Update: Fixed typo..

Good luck. -c

michaelp:

If you simply want to turn undefined elements into an empty string, you could add a step to perform the conversion immediately after the split, like so:

@line_split = map { defined($_) ? $_ : '' } split (/\t/, $line);
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...roboticus

my @line_split = split(/\t/, $line, -1);
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if (@line_split != 3) {
   die("Not enough fields in line $.\n");
}
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Thanks for all the help!

if (@line_split && $line_split[0] eq "") {
    # Has empty leading fields
}
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if (!@line_split || $line_split[0] eq "") {
    # Has empty leading fields, or no fields at all
}
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'tab-delimited file' translates to CSV file (comma separated files are common) and there are standard ways to handle such beasts. It may well be that your files are trivial and split will work fine, but in the general case there are many nasty edge cases to take care of with such files. Take a look at Text::CSV and Text::xSV.