Default Memberwise Initialization 和 Bitwise copy semantics有什么区别

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       Default Memberwist Initialization: During initialize an object, base class's constructor(s) is(are) called, data members' are called, this constructor is called. 

       Of course, this is a recursive procedure.

       Bitwise copy semantics: raw memory copy. For example, given object a of Class A occupies 10 bytes memory from address 0x0 to 0x9, 

       b = a will copy data from 0x0 to 0x9 to b's memory space if Bitwise copy semantics applies.

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