Union with pointers

Question

I have a union with two pointers to different data types:

union{
    UCHAR *_rawData;
    RGB *_RGBData;
};
typedef struct RGB
{
    UCHAR red;
    UCHAR green;
    UCHAR blue;
}RGB;

later in code ...

_rawData = new UHCAR[126];
_RGBData = new _RGBData[42]; //3 times lower than rawData

So my question is: is such a union safe? Theoretically, both variables use 126 bytes, so it should be fine, but I'm not sure why I asked here

Answer 1

The union itself is valid, but only one member of the association can be active at any time:

• Two initializations, as later in the code, are completely wrong: the first pointer will be lost.
• You must specify a way to determine which member is active.