C/C++宏之#与##

#include <iostream>

#define ToString(s) #s

int main(int argc, char *argv[])
{
    std::cout<<ToString(sssss)<<std::endl;

    return 0;
}

#include <iostream>
#define Concatenator(a, b) a##b

void ab() {
    std::cout<<"This is 'ab' function."<<std::endl;
}

int main(int argc, char *argv[])
{
    Concatenator(a, b)();

    return 0;
}