模板与重载运算符

c++的模板和重载运算符可以大大减少代码量，而且速度较快。实例：

#include<iostream>
#include<algorithm>
using namespace std;
struct point{
	int x,y;
	point(int x=0,int y=0):x(x),y(y){}
};
point operator +(const point &a,const point&b)
{
	return point(a.x+b.x,a.y+b.y);
}
ostream& operator << (ostream &out,const point&p)
{
	out<<"("<<p.x<<","<<p.y<<")";
	return out;
}
template<typename T>
T sum(T *begin,T *end){
	T *p=begin;
	T ans=0;
	for(T *p=begin;p!=end;p++)
	{
		ans=ans+*p;
	}
	return ans;
}
int main()
{
	double a[10]={1,2,3,4,5,5,6,7,8,9};
	point b[]={point(0,1),point(2,3),point(3,4)};
	cout<<sum(a+2,a+5)<<endl;
	cout<<sum(b,b+3)<<endl;
}

一个c++小测试，也可以试着把point也变成int和double通用的模板

尝试：

#include<iostream>
#include<algorithm>
using namespace std;
template<typename T>
struct point{
	T x,y;
	point(T x=0,T y=0):x(x),y(y){}
};
point operator +(const point &a,const point&b)
{
	return point(a.x+b.x,a.y+b.y);
}
ostream& operator << (ostream &out,const point&p)
{
	out<<"("<<p.x<<","<<p.y<<")";
	return out;
}
template<typename T>
T sum(T *begin,T *end){
	T *p=begin;
	T ans=0;
	for(T *p=begin;p!=end;p++)
	{
		ans=ans+*p;
	}
	return ans;
}
int main()
{
	point<int> a(1,2),b(2,3);
	point<double> c(2.333,6.666);
	cout<<a+b<<endl;
	cout<<a+c<<endl;
	cout<<b+c<<endl;
}

然后发现报错了2333，原来是定义过模板的point使用不能像原来那么随意了

#include<iostream>
#include<algorithm>
using namespace std;
template<typename T>
struct point{
	T x,y;
	point(T x=0,T y=0):x(x),y(y){}
};
template<typename T>
point<T> operator +(const point<T> &a,const point<T> &b)
{
	return point<T>(a.x+b.x,a.y+b.y);
}
template<typename T>
ostream& operator << (ostream &out,const point<T>&p)
{
	out<<"("<<p.x<<","<<p.y<<")";
	return out;
}
template<typename T>
T sum(T *begin,T *end){
	T *p=begin;
	T ans=0;
	for(T *p=begin;p!=end;p++)
	{
		ans=ans+*p;
	}
	return ans;
}
int main()
{
	point<int> a(1,2),b(2,3);
	point<double> c(2.333,6.666),d(1.23,2.22);
	cout<<a+b<<endl;
	//cout<<a+c<<endl;
	cout<<d+c<<endl;
}

注释那个地方是运行不了的，模板的特性可以说是同类无敌，跨类较难吧，比如int型和double型，脑洞大了倒是补了一下

#include<iostream>
#include<algorithm>
using namespace std;
template<typename T>
struct point{
	T x,y;
	point(T x=0,T y=0):x(x),y(y){}
};
template<typename T,typename K>
point<K> operator +(const point<T> &a,const point<K> &b)
{
	return point<K>(a.x+b.x,a.y+b.y);
}
template<typename T>
ostream& operator << (ostream &out,const point<T>&p)
{
	out<<"("<<p.x<<","<<p.y<<")";
	return out;
}
template<typename T>
T sum(T *begin,T *end){
	T *p=begin;
	T ans=0;
	for(T *p=begin;p!=end;p++)
	{
		ans=ans+*p;
	}
	return ans;
}
int main()
{
	point<int> a(1,2),b(2,3);
	point<double> c(2.333,6.666),d(1.23,2.22);
	cout<<a+b<<endl;
	cout<<a+c<<endl;
	cout<<d+c<<endl;
}

这回倒是可以正常求解了，可是这是人为的2333.。。