说明：  这是关于在C++下求结构体长度的资料。 结构体里面的变量要字节对齐，弄不明白原理，将经常求错了。 这里面有详细内容及案例。
(This is about the length of the data structure in C++. The structure inside the variable to be byte aligned, do not understand the principle, will often ask the wrong. There are the detailed content and case. )