Numeros negativos y enteros sin signo

demo.c

#include <stdint.h>
#include <commons/memory.h>

#define RUN(EXP) do { printf(#EXP); EXP; printf("\n"); } while(0)
#define EVALUATE(EXP) do { printf(#EXP " => %s\n", (EXP) ? "true" : "false"); } while(0) 

int main() {
    RUN(mem_hexdump(&(int){ -1 }, sizeof(int)));
    RUN(mem_hexdump(&(int16_t){ -1 }, sizeof(int16_t)));
    RUN(mem_hexdump(&(uint16_t){ -1 }, sizeof(uint16_t)));
    RUN(mem_hexdump(&(uint16_t) { UINT16_MAX }, sizeof UINT16_MAX));

    EVALUATE(-1 == -1);
    EVALUATE(-1 == (int16_t)-1);
    EVALUATE(-1 == (uint16_t)-1);
    EVALUATE(-1 == UINT16_MAX);
    
    printf("\n");

    EVALUATE((int16_t)-1 == -1);
    EVALUATE((int16_t)-1 == (int16_t)-1);
    EVALUATE((int16_t)-1 == (uint16_t)-1);
    EVALUATE((int16_t)-1 == UINT16_MAX);

    printf("\n");

    EVALUATE((uint16_t)-1 == -1);
    EVALUATE((uint16_t)-1 == (int16_t)-1);
    EVALUATE((uint16_t)-1 == (uint16_t)-1);
    EVALUATE((uint16_t)-1 == UINT16_MAX);
    
    printf("\n");
    
    EVALUATE(UINT16_MAX == -1);
    EVALUATE(UINT16_MAX == (int16_t)-1);
    EVALUATE(UINT16_MAX == (uint16_t)-1);
    EVALUATE(UINT16_MAX == UINT16_MAX);

    return 0;
}

output.txt

mem_hexdump(&(int){ -1 }, sizeof(int))
0x00000000: ff ff ff ff 00 00 00 00  00 00 00 00 00 00 00 00  |................|

mem_hexdump(&(int16_t){ -1 }, sizeof(int16_t))
0x00000000: ff ff 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

mem_hexdump(&(uint16_t){ -1 }, sizeof(uint16_t))
0x00000000: ff ff 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

mem_hexdump(&(uint16_t) { UINT16_MAX }, sizeof UINT16_MAX)
0x00000000: ff ff ff ff 00 00 00 00  00 00 00 00 00 00 00 00  |................|

-1 == -1 => true
-1 == (int16_t)-1 => true
-1 == (uint16_t)-1 => false
-1 == UINT16_MAX => false

(int16_t)-1 == -1 => true
(int16_t)-1 == (int16_t)-1 => true
(int16_t)-1 == (uint16_t)-1 => false
(int16_t)-1 == UINT16_MAX => false

(uint16_t)-1 == -1 => false
(uint16_t)-1 == (int16_t)-1 => false
(uint16_t)-1 == (uint16_t)-1 => true
(uint16_t)-1 == UINT16_MAX => true

UINT16_MAX == -1 => false
UINT16_MAX == (int16_t)-1 => false
UINT16_MAX == (uint16_t)-1 => true
UINT16_MAX == UINT16_MAX => true