template < typename T > void UnalignedWrite ( void * pPtr, const T & tVal )
{
    *(T*)pPtr = tVal;
}

template < typename T > void UnalignedWrite ( void * pPtr, const T & tVal )
{
    union {
        void *pVoid;
        T *pT;
    } u;

    u.pVoid = pPtr;
    *u.pT = tVal;

}

    u.pT = NULL;
    u.pVoid = pPtr;
    *u.pT = tVal;

    u.pT = NULL;
    //u.pVoid = pPtr;
    *u.pT = tVal;

K>Если обратили внимание на сам пример — там достаточно недвусмысленное название функции .

S>>Если Вы уверены, что у Вас этого нет (например работаете только на x86 процессорах), то просто запретите это предупреждение .

#pragma warning( push)
#pragma warning( disable : ???)
// код функции
#pragma warning( pop )

K>template < typename T > void UnalignedWrite ( void * pPtr, const T & tVal )
K>{
K>    *(T*)pPtr = tVal;
K>}
K>

template < typename T > void UnalignedWrite ( void * pPtr, const T & tVal )
{
  memcpy(pPtr, &tVal, sizeof(tVal));
}

3.10 Lvalues and rvalues
15. If a program attempts to access the stored value of an object through an lvalue of other than one of the following
types the behavior is undefined 48):

• the dynamic type of the object,
  
• a cv-qualified version of the dynamic type of the object,
  
• a type that is the signed or unsigned type corresponding to the dynamic type of the object,
  
• a type that is the signed or unsigned type corresponding to a cv-qualified version of the dynamic type of
  the object,
  
• an aggregate or union type that includes one of the aforementioned types among its members (including,
  recursively, a member of a subaggregate or contained union),
  
• a type that is a (possibly cv-qualified) base class type of the dynamic type of the object,
  
• a char or unsigned char type.

__________________
48) The intent of this list is to specify those circumstances in which an object may or may not be aliased.

3.9 Types
For any object (other than a base-class subobject) of POD type T, whether or not the object holds a valid
value of type T, the underlying bytes (1.7) making up the object can be copied into an array of char or
unsigned char.36) If the content of the array of char or unsigned char is copied back into the
object, the object shall subsequently hold its original value. [Example:
#define N sizeof(T)
char buf[N];
T obj; // obj initialized to its original value
memcpy(buf, &obj, N); // between these two calls to memcpy,
// obj might be modified
memcpy(&obj, buf, N); // at this point, each subobject of obj of scalar type
// holds its original value
—end example]

template < typename T > void UnalignedWrite ( void * pPtr, const T & tVal )
{
    union {
        void *pVoid;
        T *pT;
    } u;

    u.pVoid = pPtr;
    *u.pT = tVal;
}

Occasionally a programmer may encounter the following INVALID method for creating an alias with a pointer of a different type:
0 typedef union
1 {
2 uint16_t* sp;
3 uint32_t* wp;
4 } U32P;

    *reinterpret_cast<T*>(pPtr) = tVal;

K>template < typename T > void UnalignedWrite ( void * pPtr, const T & tVal )
K>{
K>    *(T*)pPtr = tVal;
K>}
K>

template < typename T, typename U > void UnalignedWrite ( U * pPtr, const T & tVal )
{
    (reinterpret_cast<T&> (*pPtr)) = tVal;
}