while (<Rdata.txt>) { 
  my ($name, $age, $reg_no )=split":";   
  $studentsDB {$reg_no}={Name => $name,  # Line 52: uninitialized reg_
+no
                    Age => $age,};}

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Are you trying to read lines from the file named Rdata.txt? If so, that won't do it. You probably want to open that file first. I think your warning message occurs because split operates on $_ in your code, and $_ is probably undefined (or at least does not have 3 ":"'s in it.

Tips from the Basic debugging checklist:

In reply to Re: How can one initialize the scalar $reg_no in hash element? by toolic
in thread How can one initialize the scalar $reg_no in hash element? by supriyoch_2008

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