Introduction
Occasionally I come to a need of a logical xor operator (^^) that, obviously,
doesn't exist in C++. However, it can be rather easily implemented.
Code listing
#define log_xor || log_xor_helper() ||
struct log_xor_helper {
bool value;
};
template<typename LEFT>
log_xor_helper &operator ||(const LEFT &left, log_xor_helper &xor) {
xor.value = (bool)left;
return xor;
}
template<typename RIGHT>
bool operator ||(const log_xor_helper &xor, const RIGHT &right) {
return xor.value ^ (bool)right;
}
Examples
0 log_xor 0 == false
0 log_xor 5 == true
8 log_xor 0 == true
8 log_xor 5 == false
Other details
- Although they don't have to have the same type, operands should be castable into a simple boolean.
- Precedence of
log_xor operator is the same as logical or's (||) one.
- If you decide to use it, I suggest you to add
log_xor keyword to the
usertype.dat file and
insert somewhere the #pragma warning(disable: 4800) line.
