How can I check whether multiple variables are equal to the same value?

Question

How do I compare multiple items? For example, I wish to check if all the variables A, B, and C are equal to the char \'X\' or all three are equal to \'O\'. (If 2 of them are

Answer 1

Just for variety:

template 
bool allequal(const T &t, const U &u) {
    return t == u;
}

template 
bool allequal(const T &t, const U &u, Others const &... args) {
    return (t == u) && allequal(u, args...);
}

if (allequal(a,b,c,'X') || allequal(a,b,c,'O')) { ... }