Interesting syntax usage I just discovered:

#include <iostream>

void fn(int x) {
    switch(x) {
        case 0:
            std::cout << "execute only if x == 0" << std::endl;
            if(false)
        case 1:
            {
                std::cout << "execute only if x == 1" << std::endl;
            }
            std::cout << "execute if x == 0 or x == 1" << std::endl;
            break;
        case 2:
            std::cout << "execute only if x == 2" << std::endl;
            break;
    }
}
int main(int argc, char* argv[]) {
    fn(0);
    std::cout << "*****" << std::endl;
    fn(1);
    std::cout << "*****" << std::endl;
    fn(2);
    return 0;
}

In case you missed it, note the "if(false)" at the end of the "case 0:"

renji@shrine:~/tmp$ g++ test.cpp && ./a.out
execute only if x == 0
execute if x == 0 or x == 1
*****
execute only if x == 1
execute if x == 0 or x == 1
*****
execute only if x == 2

Something loosely similar to the trickery used in Duff's Device, I guess. This can be used when 2 cases of a switch have different initial code and the same common code, although using it in production code will decrease readability of the code.