protected member function
<streambuf> <iostream>
Advance get pointer
Adds n to the get pointer.
The get pointer (gptr) is the internal pointer that points to the current location in the array with the buffered portion of the controlled input sequence.
参数
- n
- Value by which to increase the get pointer.
This shall be a value such that gptr()+n is in the range between eback and egptr.
数据竞争
修改*流缓冲区*对象。
对同一流缓冲区对象的并发访问可能导致数据竞争。
异常安全
基本保证：如果抛出异常，*流缓冲区*处于有效状态。
无效参数会导致未定义行为。