C++的构造函数属性初始化_静态成员_this指针代码实例讲解

c++的构造函数属性初始化_静态成员_this指针代码实例讲解

#include
using namespace std;

---

//构造函数的属性初始化列表
/*class teacher{
private:
 char* name;
public:
 teacher(char* name){
  this->name = name;
 }
 char* getname(){
  return this->name;
 }
};

class student{
private:
 char* name;
 //对象属性该如何赋值
 teacher t1;
 teacher t2;
public:
 student(char* name, char* name_t1, char* name_t2) :t1(name_t1), t2(name_t2){
  this->name = name;
  cout << "studnet构造函数" << endl;
 }
 void my_print(){
  cout << this->name << "," << t1.getname() << "," << t2.getname() << endl;
 }
};

void main(){
 student t("tom", "bo", "c");
 t.my_print();

 system("pause");
}*/

---

//c++ 通过new(delete)动态内存分配
//cmalloc(free)
/*class teacher{
public:
 char* name;
 int age;
public:
 teacher(char* name, int age){
  this->name = name;
  this->age = age;
  cout << "有参构造函数" << endl;
 }
 ~teacher(){
  cout << "析构函数" << endl;
 }
};

void main(){
 //c++ (new delete)动态内存分配
 //对象 
 //分配内存，调用了构造函数
 teacher* t1 = new teacher("tom", 20);
 //释放内存，调用了析构函数
 delete t1;

 //数组
 int* i2 = new int[10];
 delete[] i2;

 //c 动态内存分配
 //对象
 teacher* t3 = (teacher*)malloc(sizeof(teacher));
 free(t3);

 //数组
 int* t4 = (int*)malloc(sizeof(int)* 10);
 t4[2] = 6;
 free(t4);

 system("pause");
}*/

---

/*静态属性 方法
class student{
public:
 char* name;
 //静态属性
 static int total;
public:
 student(char* name){
  this->name = name;
  cout << "构造函数" << endl;
 }
 ~student(){
  cout << "析构函数" << endl;
 }
 //非静态方法可以调用静态属性
 void count(){
  total++;
  cout << total << endl;
 }
 //静态方法中只能调用静态属性
 static void count2(){
  total++;
  cout << total << endl;
 }

};
//给静态属性赋值
int student::total = 6;

void main(){
 //通过 类名::静态属性名 方法调用类中的静态属性
 //cout << student::total << endl;

 //通过 类名::静态方法() 调用静态方法
 student::count2();

 //student t1("jack");
 //t1.count();
 system("pause");
}*/

---

//类的大小
/*class a{
public:
 int i;
 int j;
 int k;
 static int m;
};

class b{
public:
 int i;
 int j;
 int k;
 void myprintf(){
  cout << "打印" << endl;
 }
};


void main(){
 cout << sizeof(a) << endl;//12
 cout << sizeof(b) << endl;//12
 //可以看到静态属性和非静态属性不在同一内存
 system("pause");
}*/

---

/*
//常函数，当前对象不能被修改，防止数据成员被非法访问
class student{
public:
 char* name;
public:
 student(char* name){
  this->name = name;
  cout << "构造函数" << endl;
 }
 //常函数
 //既不能改变指针的值，又不能改变指针指向的内容
 //const teacher* const this
 void print() const{
  //下面两句会报错
  //this->name = "tom";
  //this = (student*)0x0011;
  printf("%#x", this);
  cout << this->name << "," << endl;
 }
 void print2(){
  printf("%#x", this);
  cout << this->name << "," << endl;
 }
};
void main(){
 student t1("tom");
 const student t2("jack");
 //常量对象只能调用常量方法
 t2.print();
 //下面这句会报错
 //t2.print2();

 //非常量对象既可以调用常量方法，也可以调用非常量方法
 t1.print();
 t1.print2();

 system("pause");
}*/

---

/*
class a{
 //友元函数
 friend void change(a* a, int b);
private:
 int i;
public:
 a(int i){
  this->i = i;
 }
 void print(){
  cout << i << endl;
 }
};
//友元函数的实现，在友元函数中可以访问私有的属性
void change(a* a, int b){
 a->i = b;
}

void main(){
 a a(5);
 a.print();

 change(&a, 10);
 a.print();

 system("pause");
}*/

---

//友元类
/*
class a{
 //声明友元类  友元类可以访问a类中的所有属性
 friend class b;
private:
 int i;
public:
 a(int i){
  this->i = i;
 }
 void print(){
  cout << i << endl;
 }
};

class b{
private:
 a a;
public:
 void change(){
  a.i = 20;
 }
};
*/

//运算符重载
/*
class point{
public:
 int x;
 int y;
public:
 point(int x = 0, int y = 0){
  this->x = x;
  this -> y = y;
 }

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

//运算符重载如果放在类外面，则需要两个参数
//这里使用的是引用，不是指针，要比指针方便
point operator+(point &p1, point &p2){
 point tmp(p1.x + p2.x, p1.y + p2.y);
 return tmp;
}
point operator-(point &p1, point &p2){
 point tmp(p1.x - p2.x, p1.y - p2.y);
 return tmp;
}

void main(){
 point p1(3, 4);
 point p2(1, 2);
 point p3=p1 - p2;
 p3.print();

 system("pause");
}*/

---

//成员函数，运算符重载
//如果要在函数内部进行重载，则参数只能有一个
/*class point{
public:
 int x;
 int y;
public:
 point(int x = 0, int y = 0){
  this->x = x;
  this->y = y;
 }

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

 point operator+( point &p){
  point tmp(this->x + p.x, this->y + p.y);
  return tmp;
 }
 point operator-(point &p){
  point tmp(this->x - p.x, this->y - p.y);
  return tmp;
 }
};
void main(){
 point p1(3, 4);
 point p2(1, 2);
 point p3 = p1 - p2;
 p3.print();

 system("pause");
}*/

---

//当属性私有时，通过友元函数完成运算符重载
class point{
 //属性私有
 friend point operator+(point &p1, point &p2);
 friend point operator-(point &p1, point &p2);
private:
 int x;
 int y;
public:
 point(int x = 0, int y = 0){
  this->x = x;
  this->y = y;
 }

 void print(){
  cout << x << "," << y << endl;
 }
};
//运算符重载是放在类外面的
//这里使用的是引用，不是指针，要比指针方便
point operator+(point &p1, point &p2){
 point tmp(p1.x + p2.x, p1.y + p2.y);
 return tmp;
}
point operator-(point &p1, point &p2){
 point tmp(p1.x - p2.x, p1.y - p2.y);
 return tmp;
}

void main(){
 point p1(3, 4);
 point p2(1, 2);
 point p3 = p1 - p2;
 p3.print();

 system("pause");
}