不用加减乘除做加法

int addThroughBit1(int num1,int num2)
{
	if(num2==0)
		return num1;
	int tmp,carry;
	tmp=num1^num2;
	carry=(num1&num2)<<1;
	return addThroughBit1(tmp,carry);
}

int addThroughBit2(int num1,int num2)
{
	int tmp=num1,carry=num2;
	int sum;
	while(carry!=0)
	{
		sum=tmp^carry;
		carry=(tmp&carry)<<1;
		tmp=sum;
	}
	return tmp;
}