如何利用51单片机实现加减法计算-头文件：inc_all.h

1 #ifndef INC_ALL_H_

2 #define INC_ALL_H_

3

4 volatile unsigned char keyValue;

5 volatile unsigned char sign;

6 volatile long int opr1;

7 volatile long int opr2;

8 volatile long int SysValue=0;

9 volatile int keyCounter;

10 volatile int cnt50ms=0;