union num {
    int i;
    short s;
    float f;
    double d;
};
enum tag {SHORT, INT, FLOAT, DOUBLE};
struct vrnumber {
    num num;
    tag type;
};

vrnumber m;
switch (m.type) {
    case SHORT: //an operation ..
    case INT: //same operation ...
    case FLOAT: //same operation ...
    case DOUBLE: //same operation ...