void fun25(void)
{
    int i, j, num;
    unsigned ask = 0x8000;
	
    scanf("%d", &num);
    
    //方法一
    for (i = 0; i < 16; i++)
    {
    	printf("%d", (num & ask) ? 1 : 0);
    	ask = ask >> 1;
	}
    //方法二
	while (num != 0)
	{
		printf("%d", num % 2);
		num /= 2;
	}
}