请各位大侠帮我看看为什么我的程序编译时说ostream和istream is ambiguous symbol
#ifndef H_ADDRESS_H_ABCDE
#define H_ADDRESS_H_ABCDE
#include<iostream>
#include <list>
using namespace std;
struct Record
{
string name;
string tel;
};
class RecordList:public list<Record*>
{
friend ostream& operator <<(ostream & os,const RecordList& c_rl);
public:
void clear( )
{
iterator iter;
iterator it_end=end( );
for(iter=begin( );iter!=it_end;iter++)
{
delete *iter;
}
list<Record*>::clear( );
}
iterator erase(iterator where)
{
delete *where;
return list<Record*>::erase(where);
}
~RecordList( )
{
this->clear( );
}
};
#endif H_ADDRESS_H_ABCDE