#include <stdio.h>

union Value {
    int i;
    float f;
    char c;
};

int main() {
    union Value v;

    v.i = 42;
    printf("As int: %d\n", v.i);

    v.f = 3.14f;   // overwrites the same memory
    printf("As float: %.2f\n", v.f);
    return 0;
}