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How would you write (in C/C++) a macro which tests if an integer type (given as a parameter) is signed or unsigned?
#define is_this_type_signed (my_type) ...
835
A numeric variable is signed if it can represent both positive and negative numbers, and unsigned if it can only represent non-negative numbers (zero or positive numbers).
The XDR standard defines signed integers as integer. A signed integer is a 32-bit datum that encodes an integer in the range [-2147483648 to 2147483647]. An unsigned integer is a 32-bit datum that encodes a nonnegative integer in the range [0 to 4294967295].
while comparing a>b where a is unsigned int type and b is int type, b is type casted to unsigned int so, signed int value -1 is converted into MAX value of unsigned**(range: 0 to (2^32)-1 )** Thus, a>b i.e., (1000>4294967296) becomes false. Hence else loop printf("a is SMALL!
An int type in C, C++, and C# is signed by default. If negative numbers are involved, the int must be signed; an unsigned int cannot represent a negative number.
In C++, use std::numeric_limits<type>::is_signed.
#include <limits>
std::numeric_limits<int>::is_signed - returns true
std::numeric_limits<unsigned int>::is_signed - returns false
See https://en.cppreference.com/w/cpp/types/numeric_limits/is_signed.
87
If what you want is a simple macro, this should do the trick:
#define is_type_signed(my_type) (((my_type)-1) < 0)
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