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

// ANONYMOUS UNION TYPE inside a struct type

typedef struct {  // 'Number' will now include both the value and the type.
    union {
    //union NumberValue {
        int   as_int;
        float as_float;
        char* as_string;
    };  // with anonymous union type, we skip the field name
    //} value;
    enum NumberType {
        TYPE_UNINITIALIZED,
        TYPE_INT,
        TYPE_FLOAT,
        TYPE_STRING
    } type;   // field .type has type enum NumberType
} Number;


void print_number(Number n) {
    if(n.type == TYPE_INT) {
        printf("n has the value %d\n", n.as_int);
    }
    else if(n.type == TYPE_FLOAT) {
        printf("n has the value %.08f\n", n.as_float);
    }
    else if(n.type == TYPE_STRING) {
        printf("n has the value %s\n", n.as_string);
    }
}

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

    Number  n = { .as_int = 3, .type = TYPE_INT };
    print_number(n);

    n = (Number) { .as_float = 3.1415, .type = TYPE_FLOAT };
    print_number(n);
    
    n = (Number) { .as_string = "e",   .type = TYPE_STRING };
    print_number(n);

    printf("TYPE_INT    == %d\n", TYPE_INT);
    printf("TYPE_FLOAT  == %d\n", TYPE_FLOAT);
    printf("TYPE_STRING == %d\n", TYPE_STRING);

    return EXIT_SUCCESS;
}
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