#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>

// Q: n.value.is_int is cumbersome.  Can I just write n.as_int like before?
// A: Yes, you can.  Use an anonymous union inside the struct.  Just remove the
//    field name and type name for the union definition inside a struct definition.

struct Number {
    //union NumberValue {
    union {
        int    as_int;
        double as_double;
    //} value;
    };

    enum NumberType {
        NUMBER_INT,
        NUMBER_DOUBLE
    } type;

    char* name;
};   // << SEMICOLON <<


void print_number(struct Number n) {
    if(n.type == NUMBER_INT) {
        printf("%s: %d\n", n.name, n.as_int);
    }
    else if(n.type == NUMBER_DOUBLE) {
        printf("%s: %f\n", n.name, n.as_double);
    }
    else {
        assert(false);  // Unexpected value of type_of_n
    }
}

int main(int argc, char* argv[]) {

    /* union NumberValue n = { .as_double = 654321.123456 }; */
    /* enum NumberType type_of_n = NUMBER_DOUBLE; */

    /* union NumberValue value_of_n = { .as_int = 5 }; */
    /* enum  NumberType  type_of_n  = NUMBER_INT; */
    struct Number n = { .as_int = 5,
                        .type   = NUMBER_INT,
                        .name   = "Eff Eye Vee Yee" };

    //print_number(n, type_of_n);
    print_number(n);  // Value and type are now encapulated in one variable.

    return EXIT_SUCCESS;
}
/* vim: set tabstop=4 shiftwidth=4 fileencoding=utf-8 noexpandtab: */