Character Types in C : Distinct or Equivalent?

In C , the behavior of character types (char) can sometimes differ from that of signed and unsigned integers, leading to confusion. Specifically, the following code demonstrates this difference:

#include 

typedef   signed char       int8;
typedef unsigned char      uint8;

struct TrueType {};
struct FalseType {};

template 
struct isX
{
   typedef typename T::ikIsX ikIsX;
};

template             struct isX  { typedef FalseType ikIsX; };
template             struct isX  { typedef FalseType ikIsX; };
template             struct isX  { typedef FalseType ikIsX; };

template  bool getIsTrue();
template            bool getIsTrue() { return true; }
template            bool getIsTrue() { return false; }

int main(int, char **t )
{
   cout ::ikIsX  >() ::ikIsX  >() ::ikIsX  >() 
This code compiles but produces different results for char than for int8 and uint8. This is because C   treats char, signed char, and unsigned char as three distinct types.
In contrast, int and uint32 are equivalent types:
template             struct isX  { typedef FalseType ikIsX; };
template             struct isX  { typedef FalseType ikIsX; };
This distinction stems from the fact that char has historically been used for both representing characters and storing numeric values. As a result, C   maintains backward compatibility by treating plain char as a separate type, distinct from int.
To determine which of the two representations char uses, the implementation-defined typedef char_traits::signed is provided. If this is true, char behaves as a signed type; otherwise, it behaves as an unsigned type.