g++编译器提示以下语句错误：
template<typename Type>
class SingleList{
public:
SingleList()
{
head = new SingleListNode<Type> () ; //Error happens here!!!
}
错误信息是：
./inc/single_list.h: In instantiation of ‘SingleListNode<int>’:
./inc/single_list.h|39 col 13| instantiated from ‘SingleList<Type>::SingleList() [with Type = int]’
的定义head如下，可能问题与这里无关。
SingleListNode<Type> *head;
SingleList函数中类的实例化main是：
int main()
{
SingleList<int> list;
我不知道语法错误发生在哪里，有人可以帮助我吗？谢谢！！
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以下是源文件的内容：
template<typename Type> class SingleList;
template<typename Type> class SingleListNode{
private:
friend class SingleList<Type>;
SingleListNode() : next(NULL){}
public:
friend ostream& operator<< <Type>(ostream& os,SingleListNode<Type>& sln); //Error here!!
private:
SingleListNode *next;
};
template<typename Type> ostream& operator<<(ostream& os,SingleListNode<Type>& out){
os<<out.data;
return os;
}
template<typename Type> class SingleList{
public:
SingleList()
{
head = new SingleListNode<Type> () ; //Error happens here.
}
~SingleList(){
delete head; //Same error
}
private:
SingleListNode<Type> *head;
};
g++提示的错误信息
|| g++ -g -I ./inc/ -c single_list_test.cpp -o single_list_test.o
|| single_list.h: In instantiation of ‘SingleListNode<int>’:
single_list.h|25 col 13| instantiated from ‘SingleList<Type>::SingleList() [with Type = int]’
single_list_test.cpp|9 col 18| instantiated from here
single_list.h|10 col 18| error: template-id ‘operator<< <int>’ for ‘std::ostream& operator<<(std::ostream&, SingleListNode<int>&)’ does not match any template declaration
|| make: *** [single_list_test.o] Error 1