#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>

enum Types {
    intType, doubleType, charType, empty
};

struct Tagged{
    enum Types types;

    union {
        int a;      // if intType
        double b;   // if doubleType
        char c;     // if charType
    } value;        // if empty
};

void print(struct Tagged *data) {
    for (struct Tagged *st = data; st < data + 5; st++) {
        switch (st->types) {
        case intType: printf("union containes int value: %d\n", st->value.a); break;
        case doubleType: printf("union containes double value: %f\n", st->value.b); break;
        case charType: printf("union containes char value: %c\n", st->value.c); break;
        case empty: printf("union contains nothing\n"); break;
        default: break;
        }
    }
}

int main() {
    struct Tagged data[5];


    data[0].types = 3;

    data[1].types = 3;

    data[2].types = 0;
    data[2].value.a = 5;

    data[3].types = 2;
    data[3].value.c = 'i';

    data[4].types = 3;

    print(&data);

    return 0;
}