QUESTCOMPARE

Message        <Context> the unsigned expression "<expr>" is being
               compared with a relational operator to a constant
               whose value is not greater than zero.  This might not
               be what you intended.

Description    An ordered comparison between an unsigned value and a
               constant that is less than or equal to zero often
               indicates a programming error.  Humans consider an
               unsigned value to be larger than any negative value.
               But in C a negative value is converted to an unsigned
               value before the comparison, so any negative value
               compares larger than most unsigned values.  An
               ordered comparison of an unsigned value to zero
               suggests a programming error because the value can
               only be greater than or equal to zero.  If the code
               is correct, the comparison could be more clearly
               coded by testing for equality with zero.

User Action    Cast (or otherwise rewrite) one of the operands of
               the compare to match the signedness of the other
               operand, or compare for equality with zero.