Question

How to check whether a type is signed or unsigned in C

Answer 1

#include <stdio.h>

#define is_type_signed(t) (((t) - 1) < 0)
#define is_signed(t) printf( #t " is %s\n", is_type_signed(t) ? "signed" : "unsigned" );

int main(void)
{
    is_signed(int);
    is_signed(unsigned int);
    printf("%d\n", is_type_signed(int));
    printf("%d\n", is_type_signed(unsigned int));
    
    is_signed(char);
    is_signed(unsigned char);
    printf("%d\n", is_type_signed(char));
    printf("%d\n", is_type_signed(unsigned char));

    is_signed(long);
    is_signed(unsigned long);
    printf("%d\n", is_type_signed(long));
    printf("%d\n", is_type_signed(unsigned long));

    return 0;
}




/*
run:

int is signed
unsigned int is unsigned
1
0
char is signed
unsigned char is unsigned
1
0
long is signed
unsigned long is unsigned
1
0

*/

 

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