比较好的方法是读取一行到临时缓冲区，然后将这一行一次性拷贝到用户空间。
It would be better to read a line into a temporary buffer and then copy this to user space in one go.
分配一个临时的固定大小的wchar _ t缓冲区。
一种方法，以加强在这些情况下的表现，缓冲区中的数据：到尽可能多的数据读取到一个可以在类的临时存储阵列，然后包裹需要它。
One way to enhance performance under these conditions is to buffer the data: to read as much data as you can into a temporary storage array inside the class, then parcel it out as needed.
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