"Classes and initializers" in C

Question

#include <stdio.h>
  union test {
    int test1;
    int test2;
    int test3;
  };
  int testC(union test *x, int q, int w, int e) {
    (x->test3)=q;
        x--;
    (x->test2)=w;
        x--;
    (x->test1)=e;
        x--;
    return 0;
  };
  int main() {
    union test hi;
    testC(&hi,5,6,7);
    printf("%i, %i, %i \n", hi.test1, hi.test2, hi.test3);
        int x,*y = 0;
        x = 1;
        x++;
        scanf("%i\n", y);
  }

The above code is supposed to create an Union and then "initialize" all its components to the inputs, but instead it just initializes itself to the first one. I've tried x++ and moving the values around, but nothing seems to work.

Whats the `x--` supposed to do? Are you sure you want an union? Seems like you need a struct. — tkausl, May 11 '18 at 02:33
That `union` consists of exactly one `int`. Try printing `sizeof(union test)` and you'll see it's the same as the `sizeof(int)`. You either want a struct or an array. — user3386109, May 11 '18 at 02:37
no, it does't have to be all ints, I want to also include chars etc. — Devan S., May 11 '18 at 14:36

score 0 · Answer 1 · answered May 11 '18 at 02:37

0

A union takes up as much space as its largest member requires. That means it can only hold the value of one of its members at a time. The answer below explains it pretty well.

Difference between a Structure and a Union

answered May 11 '18 at 02:37

hmarceau

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"Classes and initializers" in C

1 Answers1