51单片机100内的加减乘除计算器C语言程序

#define uchar unsigned char   #define uint  unsigned int   char b[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,   0xa1,0x86,0x8e,0x8c,0xc1,0xce,0x91,0x89,0xc7,0xff};    // 共阴极字符码   //延时函数，用于实现程序中的短暂延时，表示延时cnt个毫秒   void delay(unsigned int cnt)   {   unsigned char i;   while(cnt--)   {   for(i=220;i>0;i--)   ;   }   }   //键盘扫描程序   uchar keyboardscan(void)   {   uchar sccode,recode;   P1=0xf0;    //P1口附初值   if((P1&0xf0)!=0xf0)//如果P1口电平不等于0xf0，表示有按键按下   {   delay(20);    //延时20毫秒后再判断，看是否还有按键按下，次步为软件防抖   if((P1&0xf0)!=0xf0)//继续判断是否有按键按下   {   sccode=0xfe;  //进行逐行判断   while((sccode&0x10)!=0)   {   P1=sccode;   if((P1&0xf0)!=0xf0)   {   recode=(P1&0xf0|0x0f);   switch((~sccode)+(~recode))   {   // 下面是键盘的编码识别   case 0x11:    return(1);    break;   case 0x21:  return(2);    break;   case 0x41:    return(3);     break;   case 0x81:    return(11);  break;//返回对应的键值0~15   case 0x12:    return(4);    break;   case 0x22:  return(5);    break;   case 0x42:  return(6);    break;   case 0x82:    return(12);   break;   case 0x14:    return(7);    break;   case 0x24:  return(8);    break;   case 0x44:  return(9);   break;   case 0x84:    return(13);  break;   case 0x18:    return(10);   break;   case 0x28:    return(15);   break;   case 0x48:  return(16);   break;   case 0x88:    return(14);  break;   default:break;   }   }   else   sccode = (sccode<1)|0x01;   }   }   }   return(0xff); //如果没有按键按下，则返回0xff   }   void output(uchar number)   {   P0=b[number/10];   P2=b[number%10];   }   int yunsuan(uchar a,uchar b,uchar c)   {   switch(c)   {   case 1:return(a/b);break;   case 2:return(a*b);break;   case 3:return(a-b);break;   case 4:return(a+b);break;   }   }   void main(void)                 //主函数   {   unsigned char n1,n2,key,index,a;   n1=n2=index=0;   P0=P2=b[0];   while(1)   {   key = keyboardscan();//键盘扫描，看是否有按键按下   if(key != 0xff)//如果有按键按下，则key不再是0xff了，显示该按键键值   {   if(key<10)   {   if(!index) n1=key%10;   else n2=key%10;   output(key%10);   }   else if(key==15)   {   n1=n2=index=0;   output(0);   }   else if(key==16)   {   if(!index) output(n1);   else   {   a=yunsuan(n1,n2,index);   a=a%100;   output(a);   n1=a;   n2=index=0;   }   }   else   {         if(index==0||n2==0) index=key-10;   else   {   a=yunsuan(n1,n2,index);   a=a%100;   output(a);   n1=a;   n2=0;   index=key-10;   }   }   }   }   }