The uninitialized value in hash element(!) would be $database. In such cases it is a good debugging technique to add statements like the following to your code to observe what happens:

use Data::Dumper;  #at the start of the script
...

print Dumper(\$database,\$nextfield,\@fields); 
$result{$database}{next}= $nextfield; $result{$database}{fields}= \@fi
+elds; #<--- the problematic line

[download]

A simple print "\$database is $database\n" would do as well, but Data::Dumper is to print for debugging like a lawnmower is to a scissor for cutting gras ;-).

Look at the output and compare it to your expectations. Probably you will see an undef value printed for $database. Now you can retrace the steps, look how $database could get that value, insert "print Dumper..." statements where you think it could go wrong. Maybe it is a regex that didn't match anything or maybe you put a value in an array into $a[1] but not in $a[0], which would leave the first array value undefined...

In reply to Re^5: Hash of Arrays or Arrays of arrays? and how proceed? by jethro
in thread Hash of Arrays or Arrays of arrays? and how proceed? by paride

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