分段故障执行方法

我编码的相关（我认为）行如下。
是什么意思是有一个群集列表。
其中一个， base ，将吸收另一个（ aborbed ）。
aborbed 群集应从列表中删除。

The relevant (I think) lines of my coding are below. What is meant is that there is a list of Clusters. One of them, base, will absorb another one (the aborbed). The aborbed cluster should be erased from the list.

我遇到的第一个问题是我需要在 base 和吸收的集群中执行其他操作，在之后循环关闭。
从我的搜索中，我找到了 =&（* li）的东西。我理解的是，我得到一个指向元素 li 指向的地址的指针，虽然我做不到 absorb = li ，因为一个是迭代器而另一个是（简单？）ponter。我很感激对此有一些解释。

First problem I encountered was that I needed to perform other operations in both base and absorbed clusters, after while cycle closes. From my searches, I found the = &(*li) stuff. What I understand is that I get a pointer to the address of the element li points to, although I cannot do absorbed = li, because one is an iterator and the other a (simple?) ponter. I'd appreciate some explanation on this.

现在，更大的问题是我在行 c-> getPoints中遇到了一个分段错误（）; 方法 joinCluster（）
我做错了什么？我应该怎么做？

Now, the bigger problem is that I get a sementation fault in the line c->getPoints(); of the method joinCluster() What am I doing wrong? What should I do an why?

我在Linux x86_64中使用g ++（GCC）4.5.2。

I'm using g++ (GCC) 4.5.2 in Linux x86_64.

Cluster * base;
Cluster * absorbed;

list<Cluster>::iterator li = clusters.begin(); 
while ( li != clusters.end() ) {   
    if (li->getId() == p2) {
        absorbed = &(*li);
        li = clusters.erase(li);
    } else if (li->getId() == p1) { 
        base = &(*li);
    }
++li;
}

base->joinCluster(absorbed);


void Cluster::joinCluster(Cluster * c)
{
    set<unsigned int> pts = c->getPoints(); 
}

set<unsigned int> Cluster::getPoints()
{
return points;
}

class Cluster {
    private:
    std::set<unsigned int> points;
    public:
    std::set<unsigned int> getPoints();
};