list iterator not dereferencable,该怎么处理

list iterator not dereferencable
1)见下程序：想从链表尾部和首部访问，使用链表后出现问题：list iterator not dereferencable。
for(list<Edge>::iterator iterEdge=allEdge.end();iterEdge!=allEdge.begin();iterEdge--)
{
if(!((*iterEdge).flag))
{
lastEdge=*iterEdge;
}
 
}

2)可以同时用两个迭代器指向同一链表的不同位置，并访问两个不同的迭代器吗？


[解决办法]

C/C++ code

#include <iostream> #include <string> #include <list> using namespace std; int main() {     string st[5] = {"opensuse","debian","redhat","minix","windows"};     list <string> ilist(st,st+5);     list <string>::reverse_iterator it;     /*    for (it = ilist.begin(); it != ilist.end(); ++it)         cout << *it << "----";     cout << endl;     */    for (it = ilist.rbegin(); it != ilist.rend(); ++it)         cout << *it << "----";     cout << endl;         /*    cout << *it << endl;                                            //1         ilist.erase(ilist.begin(),ilist.end());                    //2     cout << *it << endl;                                            //3 */        return 0; }