Union of same type in C++

问题

Whenever I see examples of union, they are always different types. For example, from MSDN:

// declaring_a_union.cpp
union DATATYPE    // Declare union type
{
    char   ch;
    int    i;
    long   l;
    float  f;
    double d;
} var1;          // Optional declaration of union variable

int main()
{
}

What happens if I have a union (in this case anonymous, but that shouldn't matter) like this:

union
{
    float m_1stVar;
    float m_1stVarAlternateName;
};

Regardless of whether this is good practice or not, will this cause any issues?

回答1:

No, this won't cause any issues. The reason you don't see it more often is that it's pointless - both names refer to the same value of the same type.

回答2:

An issue would arise only if you want to have unique values for the two variables. In your use-case, it should work fine.

来源：https://stackoverflow.com/questions/6512710/union-of-same-type-in-c