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$dataEntry =~ m{ \A   # beginning of string
                 \+?  # optional plus sign
                 \d+  # one or more digits
                 \z   # end of string
               }xms

use Regexp::Common qw( number );
$dataEntry =~ /$RE{num}{int}/ && $dataEntry == abs $dataEntry

m{ \A      # beginning of string
   \+?     # optional plus sign
...
   [0-9]*  # optional digits, including zero
   \z      # end of string
 }xms