Изменить знаковость переменной

#include <stdio.h>
 
typedef char Some_type; // Данная строчка может находится в другом модуле и
                        // содержать описание произвольного типа.
Some_type some_var;
 
int main(void)
{
    return some_var < 0;
}

#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
 
#define MODIFY_INT_TYPE(int_obj, signed_or_unsigned) (\
    sizeof(int_obj) == sizeof(char) ? (signed_or_unsigned char) int_obj : \
    sizeof(int_obj) == sizeof(short) ? (signed_or_unsigned short) int_obj : \
    sizeof(int_obj) == sizeof(int) ? (signed_or_unsigned int) int_obj : \
    sizeof(int_obj) == sizeof(long) ? (signed_or_unsigned long) int_obj : \
    (signed_or_unsigned long long) int_obj)
 
#define is_negative(var) (MODIFY_INT_TYPE(var, signed) < 0)
 
unsigned char unsigned_char = UCHAR_MAX;
unsigned short unsigned_short = USHRT_MAX;
unsigned int unsigned_int = UINT_MAX;
 
char str_positive[] = "positive";
char str_negative[] = "negative";
 
int main(void)
{
    printf("unsigned_char is %s\nunsigned_short is %s\nunsigned_int is %s\n", 
        is_negative(unsigned_char) ? str_negative : str_positive,
        is_negative(unsigned_short) ? str_negative : str_positive,
        is_negative(unsigned_int) ? str_negative : str_positive);
    return EXIT_SUCCESS;
}

typedef  int MyType ;

#define MyType int

#define CONVERT_SIGNEDNESS(signedness, integer) (\
    sizeof(integer) == sizeof(char) ? (signedness char) integer : \
    sizeof(integer) == sizeof(short) ? (signedness short) integer : \
    sizeof(integer) == sizeof(int) ? (signedness int) integer : \
    sizeof(integer) == sizeof(long) ? (signedness long) integer : \
    (signedness long long) integer)
 
#define SIGNED(integer) CONVERT_SIGNEDNESS(signed, integer)
#define UNSIGNED(integer) CONVERT_SIGNEDNESS(unsigned, integer)