为什么用getche（）接受字符之后会在屏幕输出一个a啊？

[qq_33186495]

求解释，还有为什么用getche接受输入 按下右方向键，键值是77啊，那剩下方向的键值是多少，为什么不是37，38等等

[paschen]

#define VK_LEFT 0x25 #define VK_UP 0x26 #define VK_RIGHT 0x27 #define VK_DOWN 0x28

[赵4老师]

仅供参考：

//The _getch function reads a single character from the console without echoing.
//Function can not be used to read CTRL+Break.
//When reading a function key or an arrow key,
//_getch must be called twice; the first call returns 0 or 0xE0,
//and the second call returns the actual key code.
#include <conio.h>
#include <windows.h>
void main() {
    unsigned short k;

    while (1) {
        Sleep(100);
        k=getch();
        if (27==k) break;//按Esc键退出
        if (0==k||0xe0==k) k|=getch()<<8;//非字符键
        cprintf("%04x pressed.\r\n",k);
    }
}