Why does this code work wrong?

Question

C++ / C#

Why is the result of this code not 0 but -1? Is the data type broken?

#include <stdio.h>

int main() {
    unsigned cash = 0;
    --cash;

    printf("%d", cash);

    return 0;
}

Answer 1

Because %d treats the passed value as a signed int.
Supply %u and get the unsigned value of UINT_MAX (0xFFFFFFFF).
But you still won't get zero, operations with unsigned numbers in C are performed modulo (UINT_MAX+1).