从控制台读取一个字符
MSDN上的说法:
The _getch and _getwch functions read a single character from the console without echoing the character. None of these functions can be used to read CTRL+C. When reading a function key or an arrow key, each function must be called twice; the first call returns 0 or 0xE0, and the second call returns the actual key code.
而getch
This POSIX function is deprecated beginning in Visual C++ 2005. Use the ISO C++ conformant _getch instead.