51单片机C语言程序4个独立按键实现对数码管数字显示的加减清零等

#include //P0是数码管。P1是LED.P2是按键sbit KEY_OUT_1 = P2^3;sbit KEY_OUT_2 = P2^2; sbit KEY_OUT_3 = P2^1;sbit KEY_OUT_4 = P2^0;#define uchar unsigned char#define ulint unsigned long#define Frequency 10//定时器中断时间 = f*T#define Time 1//一个周期1ms