underlying architecture 2’s complement representation

Question

The goal that I have is to look and see if the operating system is using 2’s complement underlying architecture. Going into this I was at a complete blank after a while I remembered that 1's compliment had two different representations for 0, (0000 0000) and (1111 1111). Now I havnt dealt with binary numbers to this extent within code yet. I was hopping if someone could tell me if this idea will work in telling the differences, if so i could use some hints on how to start writing this code. Thanks

Answer 1

The obvious way to learn about your platform's implementation of types is to print out the object bytes of an object of interest, e.g. a number and its negative:

int a = 5, b = -a;

const unsigned char * p = (const unsigned char *)&a;
const unsigned char * q = (const unsigned char *)&b;

for (size_t i = 0; i != sizeof(int); ++i)
    fprintf(stdout, "%02X ", p[i]);
fputc('\n', stdout);

for (size_t i = 0; i != sizeof(int); ++i)
    fprintf(stdout, "%02X ", q[i]);
fputc('\n', stdout);