【C/C++学院】0825-类模板/final_override/类模板与普通类的派生类模板虚函数抽象模板类/类模板友元/位运算算法以及类声明/Rtti 实时类型检测/高级new创建/类以及函数包装器

类模板

#pragma once

template <class  T=int>//类模板可以有一个默认的值
class myArray
{
public:
myArray();
~myArray();
};
#include "myArray.h"

template <class  T=int>//每一个函数都需要加上一个默认的值
myArray<T>::myArray()   //类模板成员函数在外部，需要加载类型初始化
{
std::cout << "构造" << typeid(T).name() << std::endl;
}

template <class  T=int>
myArray<T>::~myArray()
{
std::cout << "销毁" << typeid(T).name() << std::endl;
}
#include <iostream>
#include <array>
#include <string>
#include "myArray.h"
#include "myArray.cpp"//类模板的成员函数没有实例化，不会自动找到，需要手动包含

using namespace std;

void main2()
{
//myArray<int>   my1;

myArray<>  my2;//C++11的新功能

std::cin.get();

}

void main1()
{

array<string, 5>strarray = {"calc","mspaint","notepad","tasklist","pause"};
for (int i = 0; i < strarray.size();i++)
{
std::cout << strarray[i].c_str() << std::endl;
}
std::cin.get();
}

#include<iostream>
#include<string>
//定义两种数据类型的类模板
//STL  数据结构，算法，适用任何类型

template<class T1,class T2>
class myclass
{
public:
T1 t11;
T2 t22;
myclass(T1 t111, T2 t222) :t11(t111), t22(t222)
{

}
void print()
{
std::cout << t11 << "  "<<t22 << std::endl;
}
};

using namespace std;

void main1()
{
myclass<int, double> my1(10, 20.8);
my1.print();

myclass<double, string>my2(20.8, "123456abc");
my2.print();

std::cin.get();
}

#pragma once

template<class T,int n>
class Array
{
public:
Array();
Array(int length);
~Array();
int size();
T get(int num);
T& operator [](int num);//重载【】
void set(T data, int  num);
public:
T *pt;
//int n;//长度
};
#include "Array.h"

template<class T, int n>//int n不可以修改，不是类的内部成员
Array<T,n>::Array()
{
//this->pt = nullptr;//空指针
//this->n = 0;
this->pt = new T
;
}
template<class T, int n>//每一个函数都必须模板
Array<T,n>::Array(int length)
{
this->pt = new T[length];
//n = length;
}

template<class T, int n>//每一个函数都必须模板
Array<T,n>::~Array()
{
//n = 0;
delete[] this->pt;
}

template<class T, int n>//每一个函数都必须模板
int  Array<T,n>::size()
{
return n;
}

template<class T, int n>//每一个函数都必须模板
T Array<T,n>::get(int num)//num是数组的下标
{
if (num >= n ||num <0)//报错
{
//异常
}
else
{
return *(this->pt + num);
}
}

template<class T, int n>//每一个函数都必须模板
void Array<T,n>::set(T data, int  num)
{
if (num<0 || num>=n)
{
}
else
{
*(pt + num) = data;
}
}

template<class T, int n>//每一个函数都必须模板
T& Array<T, n>::operator [](int num)
{
if (num < 0 || num>=n)
{

}
else
{
return  *(pt + num);
}
}
#include <iostream>
#include <string>
#include "Array.h"
#include"Array.cpp"

using namespace std;

void main1()
{
/*
string str = "calc";
Array<string> myarray(5);//构造五个元素数组
for (int i = 0; i < myarray.size();i++)
{

str += "X";
myarray.set(str, i);
std::cout << myarray.get(i) << std::endl;
}
*/

std::cin.get();
}

void main22()
{
Array<int,5 > myarray;
for (int i = 0; i < myarray.size(); i++)
{
myarray.set(i, i);
std::cout << myarray[i] << std::endl;
}

std::cin.get();
}

template<class T, int n>//类模板作为参数，类型无比明确
void print(Array<T,n> &myarray)
{
for (int i = 0; i < myarray.size();i++)
{
std::cout << myarray[i] << std::endl;
}
}

void main()
{
Array<int, 5 > myarray;
for (int i = 0; i < myarray.size(); i++)
{
myarray.set(i, i);
}
print(myarray);

std::cin.get();
}

final_override

#include<iostream>
//C++11  final  override针对虚函数
//final拒绝重载,某些情况下，接口拒绝被重写
//加了final关键字的虚函数，无法被重写，预留接口
//override，警示符，声明我重写父类的方法，父类没有接口，会提示出错

class ye
{
public:
//final”函数必须是虚函数
virtual void print() final  //虚函数无法重写
{
std::cout << "爷爷\n";
}
virtual void run()
{
std::cout << "爷爷run\n";
}
};

class  ba:public ye
{
public:
//警示作用，强调我覆盖了父类的方法,必须是虚函数
void runa () override
{
std::cout << "爸爸run\n";
}
};

void main1()
{
ba ba1;
ba1.run();

std::cin.get();
}

类模板与普通类的派生类模板虚函数抽象模板类

#include <iostream>
#include <string>
//模板类之间继承

//类模板可以直接继承类模板，类型必须传递
//普通类继承类模板，需要明确类型实例化类模板
//类模板继承普通类，常规的操作方式
//类模板当作普通哦类，需要模板参数对类进行实例化

template<class T>  //抽象模板类
class myclass
{
public:
T  x;
myclass(T t) :x(t)
{

}
//virtual void print()
//{
//	std::cout << x << std::endl;
//}
virtual  void print() = 0;

};

template<class T>
class newclass :public myclass<T>  //继承必须明确类型
{
public:
T y;
newclass(T t1, T t2) :myclass(t1), y(t2)
{

}
void print()
{
std::cout << x <<"     " <<y<< std::endl;
}
};

void main()
{
myclass<int >  *p=new newclass<int>(10,9);
p->print();

std::cin.get();
}

void mainyz()
{
myclass<int> *p = new newclass<int>(10,9);
p->print();
std::cin.get();
}

void main1()
{
//newclass<double> my1(10.9, 2.3);
//my1.print();

newclass<std::string> my1("abc", "xyz");
my1.print();

std::cin.get();
}

class xyz
{
public:
int x;
int y;
int z;
xyz(int a, int b, int c) :x(a), y(b), z(c)
{

}
void  print()
{
std::cout << x << y << z;
}
};

template<class T>
class  newxyz :public xyz
{
public:
T a;
newxyz(T t1,int a1,int b1,int c1) :xyz(a1,b1,c1),a(t1)
{

}
void print()
{
std::cout << "Ta=" << a << std::endl;
std::cout << x << y << z << std::endl;
}
};

class classrun:public newxyz<int >
{
public:
int d = 1000;
classrun(int a2, int b2, int c2, int d2) :newxyz<int>(a2,b2,c2,d2)
{

}
void print()
{
std::cout << d << x << y << z << a;
}
};

void mainy()
{

classrun  run1(1, 2, 3, 4);
run1.print();

std::cin.get();
}

void mainx()
{
std::string  str1 = "china";
newxyz<std::string> new1(str1,10,90,89);
new1.print();

std::cin.get();
}

类模板友元

#include <iostream>
#include <string>
#include <vector>

template<class T> class myclass;
template<class T> void print(myclass<T> & my, T t1);

template<class T>
class myclass
{
public:
//friend  void print(myclass<T> & my, T t1);
//友元函数放在模板类的内部，实现重载
friend void print(myclass<T> & my, T t1);
friend  myclass  *  operator+(const myclass<T> & my1,
const myclass<T> &my2)
{
//myclass class1  栈，用完了马上释放

//堆上申请一个
myclass * p = new myclass(my1.x + my2.x, my1.y + my2.y);
return p;
}

myclass(T t1, T t2) :x(t1), y(t2)
{

}
//访问私有需要友元，

private:
T  x;
T  y;

};

template<class T>
void print(myclass<T> & my, T t1)
{
std::cout << typeid(t1).name() << std::endl;
std::cout << my.x << "   " << my.y << std::endl;
}

using namespace  std;
void main1()
{
myclass<int> my1(19, 29);
vector<int >  v1;
vector<	vector<int >  >  v2;
vector<vector<vector<int > > >  v3;
using VEC = vector<vector<vector<int > > >;//C++11简写
VEC v4;//等价于三维int类型数据，模板
}

void main()
{
myclass<int> my1(19, 29);
myclass<int> my2(11, 1);

print(my1, 10);
//printA(my1);
myclass<int> *pclass = my1 + my2;
print(*pclass,10);

std::cin.get();
}

位运算算法以及类声明

#include <iostream>

//加减乘除，都是靠位运算，
//将来从事手机端，嵌入式开发，位操作,
class jia;//声明，只能声明指针或者引用

jia  *pjia1;
jia *& pjia2=pjia1;
//jia & jia2;
//jia jia1;

class jia
{
public:
jia(int a, int b) :x(a), y(b)
{

}
int jiafa()
{
return x + y;
}
int getx()
{
return x;
}
int gety()
{
return y;
}
int newjiafa(int a, int b)
{
if (a == 0)
{
return b;
}
else if (b == 0)
{
return a;
}
else
{
int res = a^b;//先求结果
int wei = (a&b) << 1;//进位，左移，乘以2，
//a+b=a^b+(a&b)<<1;
std::cout << "res=" << res << " " << "wei=" << wei << "\n";
return newjiafa(res, wei);
}
}
private:
int x;
int y;
};

int newjiafa(int a,int b)
{
if (a == 0)
{
return b;
}
else if (b==0)
{
return a;//让相与慢慢趋势于0
}
else
{
int res = a^b;//先求结果
int wei = (a&b) << 1;//进位，左移，乘以2，
//a+b=a^b+(a&b)<<1;//表达式

std::cout << "res=" << res << " " << "wei=" << wei << "\n";
return newjiafa(res, wei);
}
}

void main1()
{
//std::cout << newjiafa(11, 22) << std::endl;

jia  jia1(10, 9);
std::cout << jia1.jiafa() << std::endl;
std::cout << jia1.newjiafa(jia1.getx(), jia1.gety()) << std::endl;
std::cin.get();
}

void main2()
{
int num;
std::cin >> num;
int i = 0;
while (num)
{
i++;
num &= num - 1;//让数据趋向于0
}

std::cout << i << std::endl;

std::cin.get();
std::cin.get();
}

int get1(int num)
{
int count = 0;//表示位数
unsigned int  flag = 1;//0000001  flag
//   1111  num

//0000001      1
//flag  000001
//num      1111

//flag   0000010
//num      1111

//  0000010
//flag   0000100
//num      1111

//  00000100
//flag   0001000
//num       1111

//  000001000
//flag   00010000
//num       1111
//0

while (flag)
{
std::cout << num << "  " << flag << std::endl;
if (num & flag) //不为0就自增
{
count++;
}
flag = flag << 1;
}

return count;
}

void main()
{
int num;
std::cin >> num;
int i = 0;

i = get1(num);
std::cout << i << std::endl;
std::cin.get();
std::cin.get();
}

类模板与友元函数友元类

#include<iostream>
template <class T> class myclass;
template <class T> void printA(myclass<T> my);

template <class T>
class myclass
{
public:
myclass(T t) :x(t)
{

}
friend void print(myclass<T> my)
{
std::cout << my.x << std::endl;
}
friend void printA<T>(myclass<T> my);
//友元函数如果在外部，第一声明要加类型T
//必须要声明类还有函数
private:
T x;  //模板友元类
//int y;访问与T无关的类型，普通友元类
};

template <class T>
void printA(myclass<T> my)
{
std::cout << my.x << std::endl;
}

void mainA()
{
myclass<int> my1(10);
myclass<double> my2(10.9);
printA(my1);
print(my2);

std::cin.get();
}

#include<iostream>

template <class T> class myclass;
template<class T> class runclass;//
//友元类必须声明类的存在，
//需要声明友元类，必须要与类型相关
template <class T>
class myclass
{
public:
myclass(T t) :x(t)
{

}
friend class runclass<T>;//声明友元类
private:
T x;  //模板友元类
//int y;访问与T无关的类型，普通友元类
};

template<class T>
class runclass
{
public:
void print(const myclass<T> & my)
{
std::cout << my.x << std::endl;
}
};

void main()
{
myclass<double> my1(19.8);
runclass<double> run1;
run1.print(my1);

std::cin.get();
}

类模板当作类模板参数

#include<iostream>
#include<string>
using namespace  std;

//类模板当作一个类的参数
//设计STL时候用到
//面试，类模板当作参数

template<class T>
class ren      //一个通用的类的类模板
{
public:
T name;
ren(T t) :name(t)
{

}
};

template< template<class T> class T1 >  //使用类模板当作模板参数的类
class people
{
public:
T1<string> t1x="123123";//T1必须实例化 。必须结合
T1<string>  num = "ABC"; //等价于ren类型
//T1 x;
people(T1<string> &t1)
{
std::cout << typeid(t1).name() << std::endl;
std::cout << typeid(T1).name() << std::endl;
std::cout << t1.name << std::endl;
t1x = t1;
num = t1;
}
};

void main()
{
ren<string> ren1("hello8848"); //基本数据类型

people<ren> people1(ren1);//嵌套的类模板

//std::cout << people1.t1x.name << std::endl;
//std::cout << people1.num.name << std::endl;
//std::cout << people1.str << std::endl;

std::cout << people1.t1x.name << std::endl;
std::cout << people1.num.name << std::endl;
std::cout << ren1.name << std::endl;

std::cin.get();
}

static与类模板

#include <iostream>
#include<string>

//类模板的static成员，对象，类名《类型》
//不同类型的静态成员变量，地址不一样
//相同类型的静态成员变量，地址一样
template<class T>
class myclass
{
static int data;
public:
static int num;//声明
T a;
myclass(T t) :a(t)
{
num++;
data++;
}
static void run()
{
//this->a;
std::cout << data << std::endl;
std::cout << typeid(T).name() << "\n";
}
};

template<class T>
int  myclass<T>::num = 0;
template<class T>
int  myclass<T>::data = 0;

//静态变量，静态函数，同类，共享的
//类型不同，不是共享
void main()
{
myclass<int > my1(10);
myclass<double > my2(10.9);
myclass<int > my4(10);
myclass<int>::run();
myclass<int>::run();
myclass<int>::run();
my1.run();
myclass<double>::run();
//myclass<int>::data;

std::cin.get();
}

void mainA()
{
myclass<int > my1(10);
myclass<double > my2(10.9);
myclass<std::string > my3("1234");
myclass<int > my4(10);
std::cout << &my1.num << std::endl;
std::cout << &my2.num << std::endl;
std::cout << &my3.num << std::endl;
std::cout <<&my4.num << std::endl;
std::cout << &myclass<int >::num << std::endl;
std::cout << &myclass<float >::num << std::endl;

std::cin.get();
}

类嵌套以及类模板嵌套

#include <iostream>

//类的嵌套
class myclass
{
public:
class newclass
{
public:
int num;
}new1;
};

class newnewclass :public myclass
{

};

void main2()
{
newnewclass newx;
newx.myclass::new1.num=10;

std::cout << newx.new1.num;

std::cin.get();
}

void main1()
{
myclass myclass1;
myclass1.new1.num = 19;
std::cout << myclass1.new1.num;

std::cin.get();
}

#include<iostream>

template<class T>
class myclass
{
public:
class newclass
{
public:
int num;
}new1;//定义的方式
newclass new2;

template<class V>
class  runclass
{
public:
V v1;
};//类模板后面不可以直接初始化
runclass<T> t1;
runclass<double> t2;
};

void main()
{
myclass<int > my1;
my1.new1.num = 10;
my1.t1.v1 = 12;
my1.t2.v1 = 12.9;
std::cout << my1.t1.v1 << "\n" << my1.t2.v1;

std::cin.get();
}

Rtti 实时类型检测

#include <iostream>

//rtti,实时类类型检测，
//typeid,  dynamic_cast必须依赖于虚函数表
//类型不匹配转换失败，返回为空。类型安全

//成员变量的覆盖
//虚函数有虚函数表确定数据类型
class A
{
public:
int num;
static int data;
virtual  void run()
{
std::cout << "Arun\n";
}
};

int A::data=1;

class B:public A
{
public:
int num=0;
static int data;
void run()
{
std::cout << "Brun\n";
}
void test()
{
std::cout << num<<"\n";
std::cout << "Btest\n";
}
};

int B::data = 2;

void main()
{
A a1;
B b1;
A *p1 = &a1;
A *p2 = &b1;
B *p3(nullptr);
//p3 = static_cast<B *>(p1);//直接赋地址，不安全，与虚函数无关
p3 = reinterpret_cast<B*>(p2);
std::cout << p3 << "\n";
p3->test();

std::cin.get();
}

void main3()
{
A a1;
B b1;
A *p1 = &a1;
A *p2 = &b1;
B *p3(nullptr);
//p3 = dynamic_cast<B*>(p2);
//dynamic必须要有虚函数，根据虚函数表转换，不能转换
//转换失败为空
//类的空指针可以调用不调用数据的函数
//转换成功就是地址
std::cout << p3 << "\n";
p3->test();

std::cin.get();
}

void main2()
{

//A *p1 = new A;
//A *p2 = new B;
A a1;
B b1;
A *p1 = &a1;
A *p2 = &b1;
std::cout << typeid(p1).name() <<"  "<< typeid(p2).name() << std::endl;
std::cout <<( typeid(p1) == typeid(p2))<<"\n";

std::cout << typeid(*p1).name() << "  " << typeid(*p2).name() << std::endl;
std::cout << (typeid(*p1) == typeid(*p2)) << "\n";//重载的方式判定类型是否一致

std::cin.get();

}

void main1()
{
B b1;
b1.num = 10;//覆盖现象
b1.A::num = 20;
std::cout << b1.num << "\n" << b1.A::num
<< std::endl;
std::cout << b1.data <<"   "<< b1.A::data << "\n";
std::cout << &b1.data << "   " << &b1.A::data << "\n";

std::cin.get();
}

高级new创建

#include <iostream>

class myclass
{
public:
myclass()
{
std::cout << "创建\n";
}
~myclass()
{
std::cout << "销毁\n";
}
};

void main()
{
char *pcathe = new char[1024];
char *pcatheend = pcathe + 1024;
std::cout <<(void*) pcathe << "   " << (void*)pcatheend << std::endl;

myclass *p = new(pcathe)myclass[10];//限定区域分配内存，覆盖模式
std::cout << p << std::endl;

//delete[] p;一般不需要delete.自动覆盖
std::cout << p << std::endl;

p = new(pcathe)myclass[10];
std::cout << p << std::endl;

//delete[] p;//只能释放一次
std::cout << p << std::endl;

/*
myclass *pclass = new  myclass[10];
std::cout << pclass << std::endl;
delete []pclass;
pclass = NULL;
std::cout << pclass << std::endl;
pclass = new  myclass[10];
std::cout << pclass << std::endl;
delete [] pclass;
std::cout << pclass << std::endl;
*/

std::cin.get();
}

类以及函数包装器

#include<iostream>

template<typename T,typename F>
T run(T t, F f) //包装器，实现一个操作接口，操作多个类的方法
{
return  f(t);
}

int add(int num)
{
return num + 10;
}

class myclass
{
public:
int  num;
myclass(int data) :num(data)
{

}
int operator ()(int X)
{
return X*num;
}
};

class myclassA
{
public:
int  num;
myclassA(int data) :num(data)
{

}
int operator ()(int X)
{
std::cout << "A\n";
return X-num;
}
};

void main()
{
myclass my1(5);
std::cout << run(101,my1) << std::endl;
std::cout << run(101, myclassA(51)) << std::endl;

std::cin.get();
}

void main1()
{
auto  num = 100;
auto  func = add;
std::cout << run(num, add) << std::endl;

std::cin.get();
}

类成员函数指针

#include<stdio.h>

int addC(int a, int b)
{
return a + b;
}

void  run()
{
printf("\nrun");
}

void main1()
{
int(*p)(int, int) = addC;
void(*p1)() = run;
printf("%d\n", p(1, 2));
printf("%d\n", (*p)(1, 2)); //*p编译器自动将*p解释为p
printf("%d\n", (**********p)(1, 2)); //*p编译器自动将*p解释为p

printf("%d\n", (&(**p))(1, 2)); //&没有*不可以执行，超过两个地址就不可以
//&p不能，
//printf("%d\n", (&(p))(1, 2));
printf("%p,%p,%p", &p, *p, p);
printf("\n%p,%p,%p", &p1, *p1, p1);
//printf("%d\n", (&p)(1, 2));
//取地址，取就是CPU即将调用函数执行，C语言内嵌ASM
//老版本，*p,p,&p

getchar();
}

#include <stdio.h>
#include<iostream>

void add(int a, int b)
{
std::cout << a + b << std::endl;
}

void mainA()
{

void(*p)(int, int) = add;
p(1, 2);
(*p)(1, 2);//函数指针，会被当作指针来处理，*p与p效果一样
(**************p)(1, 2);//函数指针，会被当作指针来处理，*p与p效果一样
(*&p)(1, 2);
(*******&p)(1, 2);
std::cout << (void *)p << "  " << (void *)(*p) << std::endl;
std::cout << typeid(p).name() << std::endl;
std::cout << typeid(*p).name() << std::endl;
std::cout << typeid(&p).name() << std::endl;
std::cout << typeid(*&p).name() << std::endl;
//C++编译器会自动将*p处理为p
//
std::cin.get();
}

#include<iostream>
#include<stdio.h>

//类成员函数指针，类成员函数指针数组，类成员二级函数指针

class com
{
private:
int a;
int b;
public:
com(int x, int y) :a(x), b(y)
{

}
int  jia(int a, int b)
{
return a + b;
}
int  jian(int a, int b)
{
return a - b;
}
int  cheng(int a, int b)
{
return a * b;
}
int  chu(int a, int b)
{
return a / b;
}
};

void main1x()
{
com com1(100, 20);
auto fun1 = &com::jia;
int(com::*p)(int, int) = &com::jia;
std::cout << (com1.*p)(10, 20) << std::endl;//引用对象，类成员函数指针
std::cout << typeid(p).name() << std::endl;
std::cout << typeid(fun1).name() << std::endl;

std::cin.get();
}

typedef int(com::*P)(int, int);
void main()
{
com com1(100, 20);
//P fun1[4] = { &com::jia, &com::jian, &com::cheng, &com::chu };
//类成员函数指针数组
int(com::*fun1[4])(int, int) = { &com::jia, &com::jian, &com::cheng, &com::chu };
for (int i = 0; i < 4; i++)
{
std::cout << (com1.*fun1[i])(10, 20) << std::endl;
}

int(com::**funp)(int, int) = fun1;//指向类成员函数指针的指针
for (; funp < fun1 + 4; funp++)
{
std::cout << (com1.**funp)(10, 20) << std::endl;
printf("%p", *funp);
}

for (int i = 0; i < 4; i++)
{
auto func = fun1[i];
std::cout << typeid(func).name() << std::endl;
printf("%p", func);
}

std::cin.get();
}