set/multiset自定义排序与查找规则

介绍

排序重载 <
查找重载 ()

Demo

struct XXX
{
	int a;
	int b;

	bool operator<(const struct XXX& xxx) const
	{
		return this->a < xxx.a;
	}

	bool operator()(const struct XXX& xxx)const
	{
		if (this->b == xxx.b)
		{
			return true;
		}

		return false;
	}
};

void t()
{
	std::multiset<XXX> s;

	XXX xxx;
	xxx.a = 3;
	xxx.b = 5;

	s.insert(xxx);
	xxx.b = 0;
	xxx.a = 1;
	s.insert(xxx);

	xxx.a = 2;
	s.insert(xxx);
	

	for (auto it : s)
	{
		std::cout << it.a << " ";
	}

	xxx.b = 5;

	auto it = std::find_if(s.begin(), s.end(), xxx);
	if (it == s.end())
	{
		std::cout << "not found" << std::endl;
	}
	else
	{
		std::cout << "found: " << it->a << " -> " << it->b << std::endl;
	}
	

}

map同样适用，只不过形参要加上pair