模板 Templates
語法格式
template<typename/class 類型參數(shù)表> //一般不用class
返回類型 函數(shù)模板名(函數(shù)參數(shù)列表)
{
函數(shù)模板定義體
}
函數(shù)模板 應(yīng)用條件 1.函數(shù)名相同 2.函數(shù)的參數(shù)個數(shù)相同 3.函數(shù)的參數(shù)類型不同4.函數(shù)體相同
#include<cstring>
#include <iostream>
using namespace std;
template<typename T>
class MyVector{
public:
MyVector(int size=0);//構(gòu)造
MyVector(const MyVector&obj);//拷貝
~MyVector();//析構(gòu)
T& operator[](int index);//重新定義[]
MyVector& operator=(const MyVector&obj);//重新定義=
template<typename T1>
friend ostream& operator <<(ostream &out,MyVector<T1> &obj);//重新定義<<
template<typename T1>
friend istream& operator >>(istream &in,MyVector<T1> &obj);//重新定義>>
static int a;//放在私有用set get出來 //兩個不同類型的類模板不共用一個靜態(tài)變量
private:
T*m_space;
int m_len;
};
template<typename T>//靜態(tài)變量
int MyVector<T>::a=10;
template<typename T>//每段都要加
MyVector<T>::MyVector(int size)//作用域后都要加<T>
{
m_len=size;
m_space=new T[m_len];
memset(m_space,0,sizeof(T)*m_len);
}
template<typename T>
MyVector<T>::MyVector(const MyVector&obj)
{
m_len=obj.m_len;
m_space=new T[m_len];
for(int i=0;i<m_len;i++)
{
m_space[i]=obj.m_space[i];
}
}
template<typename T>
MyVector<T>::~MyVector()
{
if(NULL!=m_space)
{
delete []m_space;
m_space=NULL;
m_len=0;
}
}
template<typename T>
T& MyVector<T>::operator[](int index)
{
return m_space[index];
}
template<typename T>
MyVector<T>& MyVector<T>::operator=(const MyVector<T>&obj)
{
delete[]m_space;
m_len=obj.m_len;
m_space=new T[m_len];
for(int i=0;i<m_len;i++)
{
m_space[i]=obj.m_space[i];
}
return *this;
}
template<typename T1>
ostream& operator <<(ostream &out,MyVector<T1> &obj)
{
for(int i=0;i<obj.m_len;i++)
{
out<<obj.m_space[i]<<endl;
}
return out;
}
template<typename T1>
istream& operator >>(istream &in,MyVector<T1>&obj)
{
for(int i=0;i<obj.m_len;i++)
{
in>>obj.m_space[i];
}
return in;
}
#include <iostream>
using namespace std;
class Teacher
{
public:
Teacher();
Teacher(const char*name,int age);
Teacher(const Teacher&obj);
~Teacher();
Teacher& operator =(const Teacher&obj);
friend ostream&operator <<(ostream&out,const Teacher&obj);
private:
char *m_name;
int m_age;
};
Teacher::Teacher()
{
m_age=0;
m_name=new char[1];
strcpy(m_name,"");
}
Teacher::Teacher(const char*name,int age)
{
m_age=age;
m_name=new char[strlen(name)+1];
strcpy(m_name,name);
}
Teacher::Teacher(const Teacher&obj){
m_age=obj.m_age;
m_name=new char[strlen(obj.m_name)+1];
strcpy(m_name,obj.m_name);
}
Teacher::~Teacher()
{
if(NULL!=m_name)
{
delete[]m_name;
m_name=NULL;
m_age=0;
}
}
Teacher& Teacher::operator =(const Teacher&obj)
{
if(m_name!=NULL)
{
delete[]m_name;
m_name=NULL;
}
m_age=obj.m_age;
m_name=new char[strlen(obj.m_name)+1];
strcpy(m_name,obj.m_name);
return *this;
}
ostream&operator <<(ostream&out,const Teacher&obj)
{
out<<obj.m_name<<" "<<obj.m_age<<endl;
return out;
}
#include"myvector.h"
#include"teacher.h"
int main()
{
MyVector<int> a(10);//T=int
for(int i=0;i<10;i++)
{
a[i]=i+100;
}
// cin>>a;
MyVector<int> b(a);
cout<<b[2]<<b[1]<<endl;
MyVector<int> c;
c=a;
cout<<c[2]<<c[1]<<endl;
cout<<a<<endl;
MyVector<Teacher> tech(3);//T=class
Teacher t1;
Teacher t2("wangnan",25);
Teacher t3(t2);
tech[0]=t1;
tech[1]=t2;
tech[2]=t3;
cout<<tech<<endl;
MyVector<Teacher*> tech1(3);//T=class*
tech1[0]=&t1;
tech1[1]=&t2;
tech1[2]=&t3;
cout<<*tech1[0]<<endl;
cout<<*tech1[1]<<endl;
cout<<*tech1[2]<<endl;
return 0;
}
模板定義很特殊森逮。由 template<…> 處理的任何東西都意味著編譯器在當(dāng)時不為它分配存儲空間晓勇，它一直處于等待狀態(tài)直到被一個模板實(shí)例告知稻艰。在編譯器和連接器的某一處，有一機(jī)制能去掉指定模板的多重定義译打。所以為了容易使用，幾乎總是在頭文件中放置全部的模板聲明和定義,文件后綴為.hpp
