请问这个case 3为什么不能执行？

正文摘要:

#include <reg51.h> #define LED P0 sbit P17=P1^7; sbit LSA=P2^0; sbit LSB=P2^1; sbit LSC=P2^2; unsigned char code discode[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f}; unsigned char ...