Undefined subroutine &Module::CoreList::is_core called at test1.pl line 9.

Older versions of Module::CoreList do not have the  is_core() function. This suggests you are working with an older version of Perl, but I cannot see that you have ever stated what version you have; this would be useful information. You can work around this:

c:\@Work\Perl\monks>perl -wMstrict -le
"print 'perl version: ', $];
 ;;
 use Module::CoreList;
 print 'Module::CoreList version: ', $Module::CoreList::VERSION;
 ;;
 my @moduleList = qw(Data::Dumper  File::stat  File::Find);
 ;;
 foreach my $module (@moduleList) {
   printf qq{'$module' };
   if (defined(my $fr = Module::CoreList->first_release($module))) {
     print qq{is a core module and was released: '$fr'};
     }
   else {
     print qq{is not core module};
     }
   }
"
perl version: 5.008009
Module::CoreList version: 2.24
'Data::Dumper' is a core module and was released: '5.005'
'File::stat' is a core module and was released: '5.004'
'File::Find' is a core module and was released: '5'
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I have also run your code but it is also showing some error.

"Some" error?!? "It doesn't work" is useless as an error report. What error? Please see I know what I mean. Why don't you?

Please resolve the issues in my full code that I have posted earlier.

I understand that you may be under pressure to do your job. However, PerlMonks is entirely a volunteer effort and the right person to help you may not be available at a given moment (or ever). Please help us to help you, e.g., by giving full information on "some error" that the code exhibits. Please see How (Not) To Ask A Question.