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

// UNION

//#define INT   1
//#define FLOAT 2
enum ValueType {  // name just like a struct or union type, capital camel case
    INT,
    FLOAT
};
// Use enum type for a variable that represents a choice or category.
// Internally, it will be stored just like an int (4 bytes on our platform).
// Fields will be automatically numbered (and distinct).
// Field list is comma separated (different from struct or union).
// Name fields with all caps, underscore case (INT_TYPE not intType or IntType or int_type)

union Value {
    int   as_int;    //   4 bytes (on our platform)
    float as_float;  //   4 bytes (on our platform)
};                   //   4 bytes (on our platform) for a 'union Value' object
//  could have done typedef union { ... } Value;

//void print_value(union Value n, int which) {   // WRONG:  Do not use int constant as flag
void print_value(union Value n, enum ValueType which) {   // GOOD
    if(which == INT) {
        printf("n.as_int == %d\n", n.as_int);
    }
    if(which == FLOAT) {
        printf("n.as_float == %.4f\n", n.as_float);
    }
}

int main(int argc, char* argv[]) {
    union Value n = { .as_int = 5 };
    print_value(n, INT);

    return EXIT_SUCCESS;
}
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