Re: How to determine if something is numeric?

[stefp]

If by numeric, you means a string that represents a natural integer in the decimal numeration system which first digit is not a zero, it happens to be a string $s that is left unchanged by the operation: $s+0

 print   +($_+0 eq $_ ? '    ' : 'not '). "numeric: $_\n" for qw( 1 01
+ a01 -3 -01 .1 )
    numeric: 1
not numeric: 01
not numeric: a01
    numeric: -3
not numeric: -01
not numeric: .1

oops, I read you specif without reading the code. I came with the same solution as you.