C++安全方便高效地复制对象数组

　　下面是第二种写法，这种写法，把内置类型的判断提出来，可以方便其它地方使用：

template<bool A，typename B，typename C>
struct _if{};

template<typename B，typename C>
struct _if<true，B，C>{ typedef B Type; };

template<typename B，typename C>
struct _if<false，B，C>{ typedef C Type; };

template<typename T，size_t N>
inline size_t ARRAYSIZE(T (&)[N])
{
&nbsp;&nbsp;&nbsp; return N;
}

template<typename T>
struct IsInnerType { static const bool Value = false; };

template<>
struct IsInnerType<bool> { static const bool Value = true; };
template<>
struct IsInnerType<char> { static const bool Value = true; };
template<>
struct IsInnerType<short> { static const bool Value = true; };
template<>
struct IsInnerType<int> { static const bool Value = true; };
template<>
struct IsInnerType<long long> { static const bool Value = true; };
template<>
struct IsInnerType<unsigned char> { static const bool Value = true; };
template<>
struct IsInnerType<unsigned short> { static const bool Value = true; };
template<>
struct IsInnerType<unsigned int> { static const bool Value = true; };
template<>
struct IsInnerType<unsigned long long> { static const bool Value = true; };

template<typename T，size_t N>
struct ArrayAssignInnerType
{
&nbsp;&nbsp;&nbsp; static inline void Invoke(T (&A)[N]， T (&B)[N])
&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; memcpy(A，B，sizeof(A));
&nbsp;&nbsp;&nbsp; }
};

template<typename T，size_t N>
struct ArrayAssignCustomType
{
&nbsp;&nbsp;&nbsp; static inline void Invoke(T (&A)[N]， T (&B)[N])
&nbsp;&nbsp;&nbsp; {
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; for(size_t i = 0; i < N; ++i)
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; A[i] = B[i];
&nbsp;&nbsp;&nbsp; }
};

template<typename T，size_t N>
inline void ArrayAssign(T (&A)[N]， T (&B)[N])
{
&nbsp;&nbsp;&nbsp; _if<IsInnerType<T>::Value，ArrayAssignInnerType<T，N>，ArrayAssignCustomType<T，N> >::Type::Invoke(A，B);
}

　　经过上面的处理，我们可以不用担心效率问题；同时，写起来也方便很多，而且不会出错。直接按如下写OK了：

ArrayAssign(B，A);

　　以上代码在VC和GCC下编译通过。