Can a positive number have the same binary code as a negative number?

Answer 1

No and Yes...

No because as such the two numbers are different and convention will define what the bit pattern should represent.

However, with 16 bits, the UNSIGNED bit pattern for 32768 is the same as the SIGNED pattern for -32768 BUT the two numbers are being represented in different ways (ie in different number systems).

If the binary representation is a SIGNED number then the top bit will be set if it is negative and with 16 bits the possible range of numbers is -32768 to +32767 and so it is IMPOSSIBLE to represent +32768.

With an UNSIGNED number of 16 bits the top bit has no such special meaning and the range possible is 0 to +65535, so it is IMPOSSIBLE to represent -32768.

ie it is IMPOSSIBLE with 16 bits to represent -32768 and +32768 in the same number system as they have the same bit pattern, BUT in different number systems the bit pattern can be used to represent the two numbers as the different number systems cannot represent BOTH -32678 and +32768.

Answer 2

No. The whole IDEA of such a code is that there is no ambiguity.

Answer 3

No, it cannot.