Why is there no ^^ operator in C/C++?

Question

& has &&. | has ||. Why doesn't ^ have ^^?

I understand that it wouldn't be short-circuiting, but it would have different semantics. In C, true is really any non-zero value. Bitwise XOR is not always the same thing as logical XOR:

int a=strcmp(str1,str2);// evaluates to 1, which is "true"
int b=strcmp(str1,str3);// evaluates to 2, which is also "true"
int c=a ^^ b; // this would be false, since true ^ true = false
int d=a ^ b; //oops, this is true again, it is 3 (^ is bitwise)

Since you can't always rely on a true value being 1 or -1, wouldn't a ^^ operator be very helpful? I often have to do strange things like this:

if(!!a ^ !!b) // looks strange

Answer 1

Dennis Ritchie answers

There are both historical and practical reasons why there is no ^^ operator.

The practical is: there's not much use for the operator. The main point of && and || is to take advantage of their short-circuit evaluation not only for efficiency reasons, but more often for expressiveness and correctness.
[...]
By contrast, an ^^ operator would always force evaluation of both arms of the expression, so there's no efficiency gain. Furthermore, situations in which ^^ is really called for are pretty rare, though examples can be created. These situations get rarer and stranger as you stack up the operator--

if (cond1() ^^ cond2() ^^ cond3() ^^ ...) ...

does the consequent exactly when an odd number of the condx()s are true. By contrast, the && and || analogs remain fairly plausible and useful.

Answer 2

Technically, one already exists:

a != b

since this will evaluate to true if the truth value of the operands differ.

Edit:

Volte's comment:

(!a) != (!b)

is correct because my answer above does not work for int types. I will delete mine if he adds his answer.

Edit again:

Maybe I'm forgetting something from C++, but the more I think about this, the more I wonder why you would ever write if (1 ^ 2) in the first place. The purpose for ^ is to exclusive-or two numbers together (which evaluates to another number), not convert them to boolean values and compare their truth values.

This seems like it would be an odd assumption for a language designer to make.