跨平台的检测键盘是否有键按下并返回按键的值

/*** @return 0:没有按键按下*  其他:有键按下，返回键的值*/int GetCharIfKbhit(void);#ifdef _WINDOWS_#include <conio.h>int GetCharIfKbhit(void){int res = _kbhit();if(res)res = _getch();return res;}#else#include <termios.h>#include <fcntl.h>int GetCharIfKbhit(void){struct termios oldt, newt;int ch;int oldf;tcgetattr(STDIN_FILENO, &oldt);newt = oldt;newt.c_lflag &= ~(ICANON | ECHO);tcsetattr(STDIN_FILENO, TCSANOW, &newt);oldf = fcntl(STDIN_FILENO, F_GETFL, 0);fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);ch = getchar();tcsetattr(STDIN_FILENO, TCSANOW, &oldt);fcntl(STDIN_FILENO, F_SETFL, oldf);return ch;}#endif