Question

keil c 的错误error C141: syntax error near '='

#include <reg51.h>
#define SW_Port P2;
sbit buzzer=P3^7;
unsigned char keys;
unsigned char code tone[]= {115, 102, 91, 86, 77, 68, 61, 57 };
void sound(unsigned char);
void delay8us(unsigned char);
main()
{ while (1)
{ SW_Port=0xff;
keys=~SW_Port;
switch (keys)
{ case 0x01:sound(0);break;
case 0x02:sound(1);break;
case 0x04:sound(2);break;
case 0x08:sound(3);break;
case 0x10:sound(4);break;
case 0x20:sound(5);break;
case 0x40:sound(6);break;
case 0x80:sound(7);break;
default:buzzer=1;break;
}
}
}
void sound(unsigned char x)
{ unsigned char i;
for (i=0;i<60;i++)
{ buzzer=0; delay8us(tone[x]);
buzzer=1; delay8us(tone[x]);}
}
void delay8us(unsigned char x)
{ unsigned char i,j;
for (i=0;i<x;i++)
for (j=0;j<1;j++);
}
这句出现错误 { SW_Port=0xff;

Answer 1

因为你在定义SW_Port时#define .... P2; P2后面有个分号，那么SW_Port就相当于“P2;”了
所以编译器在使用就相当于“P2;=0xff;”，这句当然是错的
所以在预定义的时候，千万记住，你定义中写的任何字符都会被引用进去