Question

map 简单问题，输出时提示iterator not dereferencable

list<map<int,A>> lista;
for(int i = 0;i<5;i++)
{
map<int,A> m_map;
for(int j=0;j<2;j++)
{
A aa1(i,j);
m_map.insert(map<int,A>::value_type(j,aa1));
}
lista.push_back(m_map);
}
list<map<int,A>>::iterator mlist;
map<int,A>::iterator nmap;
for (mlist=lista.begin();mlist!=lista.end(); ++mlist)
{
for(nmap = (*mlist).begin();nmap!=(*mlist).end(); ++nmap);
{
cout<<"map:first--"<<nmap->first<<";sencod--"<<nmap->second.getAdd()<<endl;
}
}

Answer 1

for(nmap = (*mlist).begin();nmap!=(*mlist).end(); ++nmap);

最后多了个 ;
这样你就会一直循环到(*mlist).end()，而下面一行的操作就是对不可访问迭代器取值了，去掉分号即可