[英]C++ template class with non-type parameter: how to overload the assign operator?
[英]how to overload << operator of class template with non-type parameter?
我正在嘗試重載類模板的operator<<
,如下所示:
template<int V1,int V2>
class Screen
{
template<int T1,int T2> friend ostream& operator<< (ostream &,Screen<T1,T2>&);
private:
int width;
int length;
public:
Screen():width(V1),length(V2){}
};
template<int T1,int T2>
ostream& operator<< (ostream &os,Screen<T1,T2> &screen)
{
os << screen.width << ' ' << screen.length;
return os;
}
上面的代碼運行正確!但我想知道是否有任何方法通過不將它設置為函數模板來重載operator<<
:
friend ostream& operator<< (ostream &,Screen<T1,T2>&);
?
是的,但您必須預先聲明模板並使用<>
語法:
template<int V1, int V2> class Screen;
template<int T1, int T2> ostream &operator<< (ostream &,Screen<T1,T2> &);
template<int V1, int V2>
class Screen
{
friend ostream& operator<< <>(ostream &, Screen&);
...
好的做法是有一些像這樣的公共功能printContent
-
void Screen::printContent(ostream &os)
{
os << width << ' ' << length;
}
ostream& operator<< (ostream &os,Screen<T1,T2> &screen)
{
screen.printContent(os);
return os;
}
因此你不需要任何friend
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.