用加法实现两个整数乘法操作

int get_multi_value(int a, int b)
{
	int res = 0;
	int sign = 1;
	if(b < 0)
	{
		b = -b;
		sign = -1;
	}

	while(b)
	{
		if(b&0x1)res+=a;
		a<<=1;
		b>>=1;
	}

	if(sign == -1)res = -res;
	return res;
}

int main()
{
	cout<<get_multi_value(-5, -6)<<endl;

	return 0;
}