倒数100

#include <reg52.h>
#define uint unsigned int
#define uchar unsigned char

uchar duan[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};
sbit w1=P2^0;
sbit w2=P2^1;
uint num=0;
void delay(uint n)
{
   while(n--);
   
   }

main()
{
   while(1)
   {
        w1=0;
    w2=0;
    P3=duan[num%10];
    P2=duan[num/10];
       delay(50000);
       num++;
       if(num==99)
      { 
         num=0;
       }
    }    
 }