Union initialization in C++ and C

Question

I have built a working C library, that uses constants, in header files defined as

typedef struct Y {
  union {
    struct bit_field bits;
    uint8_t raw[4];
  }         


        

Answer 1

I believe that C++11 allows you to write your own constructor like so:

union Foo
{
    X x;
    uint8_t raw[sizeof(X)];

    Foo() : raw{} { }
};

This default-initializes a union of type Foo with active member raw, which has all elements zero-initialized. (Before C++11, there was no way to initialize arrays which are not complete objects.)