What is the difference between signed and unsigned int

Question

What is the difference between signed and unsigned int?

Answer 1

In practice, there are two differences:

1. printing (eg with cout in C++ or printf in C): unsigned integer bit representation is interpreted as a nonnegative integer by print functions.
2. ordering: the ordering depends on signed or unsigned specification.

this code can identify the integer using ordering criterion:

char a = 0;
a--;
if (0 < a)
    printf("unsigned");
else
    printf("signed");