You might want to look at Regexp::Common::number in general, but I don't see anything ready-made to do what you want. Here's a pattern I might use:

$dataEntry =~ m{ \A   # beginning of string
                 \+?  # optional plus sign
                 \d+  # one or more digits
                 \z   # end of string
               }xms
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Using Regexp::Common, that might be:

use Regexp::Common qw( number );
$dataEntry =~ /$RE{num}{int}/ && $dataEntry == abs $dataEntry
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If you want to allow for white space in your data entry, you could add \s* into your patterns.

Update: After consideration of the contributions of the other monks, I think this is a better expression than the one I have above:

m{ \A      # beginning of string
   \+?     # optional plus sign
   [0-9]*  # optional digits, including zero
   [1-9]   # mandatory non-zero digit
   [0-9]*  # optional digits, including zero
   \z      # end of string
 }xms
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This incorporates Nkuvu's observation that a value of zero should not be allowed and mreece's suggestion that \d is not always the best way to match digits (though I find this counterintuitive). It also passes my own test suite.