编一个程序，输入一个正整数，判定它是否为回文数。当输入的数为0时，则退出程序。

#include <math.h>

unsigned GetBit(unsigned num, int bit)
{
if (bit < 1) return 0;
return (unsigned)((num-((int)(num/pow((float)10,bit))) *pow((float)10,bit))/pow((float)10, bit-1)) ;
}

void main()
{
int num,len,i;

while(scanf("%d", &num))
{
len = 0;
if (!num) break;
i = num;
while( i > 0)
{
i = i/10;
len++;
}

for(i=len; i>len/2; i--)
{
if ( GetBit(num,i) != GetBit(num,len-i+1) )
{
printf("No\n");
i=-1;
break;
}
}
if (i!=-1)
printf("Yes\n");
}
}