不能理解这个程序中检查自变量号的错误?

int a = 0, b, c, e, n = 25;
e = n;

while(n!=0)
{
  n=n/10;
  a++;
}

printf("%d",a);

b = e * e;
c = b % (pow(10, a));
if(c==e)
  printf("automorphic");
int a = 0, b, c, e, n = 25;
e = n;

while(n!=0)