因為這幾天在重學c++，說來也是慚愧，以前學習的時候一般學到多型那裡就結束了，後面的模板類和stl都沒有看過

終於下定決心看了看，發現模板類很方便，上demo

#include<iostream>
using namespace std;

struct Point {
  int x, y;
  Point(int x=0, int y=0):x(x),y(y) {}
};

//ostream 是輸出流
ostream& operator << (ostream &out, const Point& p) {
  out << "(" << p.x << "," << p.y << ")";
  return out;
}

//該模板類用來交換兩個變數的值
template<typename T>
void swap3(T& a,T& b)
{
	T t = a;
	a = b;
	b = t;
}

int main() {
  Point a(1,2),b(3,4);
  cout<<"a:"<<a<<"  b:"<<b<<endl;
  swap3(a,b);
  cout<<"a:"<<a<<"  b:"<<b<<endl;
  return 0;
}