关于c++类的赋值的问题

class jctree{public:jctree(string na, bool is, int res, int co = 0) :name(na), is_leaf(is), result(res) ,count(co){}string name;jctree operator = (jctree& jc){jctree c(jc.name, jc.is_leaf, jc.result,jc.count);c.jclist = jc.jclist;return c;}map<int, jctree>jclist;int count;bool is_leaf;int result;jctree& addattr(int attr, jctree& jc){jclist.insert(make_pair(attr,jc));count++;  return *this;}};

for (auto i = jc.jclist.begin(); i != jc.jclist.end()&&idex>=0; i++)
{


if (a[idex] == i->first)
{
jctree jj(i->second);

jc = jj;


break;
}
}

这里如果不用  jj保存i->second的结果，而直接复制给jc将引发错误。
’因为i->second是 jc里面的jclist的内容，自己的一部分，赋值给自己将引发错误。