C++语言基础 this和static关键字

#include <iostream>
using namespace std;

class Student{
public:
  void setname(char *name);
  void setage(int age);
  void setscore(float score);
  void show();
private:
  char *name;
  int age;
  float score;
};

void Student::setname(char *name){
  this->name = name;
}
void Student::setage(int age){
  this->age = age;
}
void Student::setscore(float score){
  this->score = score;
}
void Student::show(){
  cout<<this->name<<"的年龄是"<<this->age<<"，成绩是"<<this->score<<endl;
}

int main(){
  Student *pstu = new Student;
  pstu -> setname("李华");
  pstu -> setage(16);
  pstu -> setscore(96.5);
  pstu -> show();

  return 0;
}

#include <iostream>

using namespace std;

class Student {
public:
  Student(char *name, int age, float score);
  void show();
public:
  static int m_total; // 静态成员变量
private:
  char *m_name;
  int m_age;
  float m_score;
};

int Student::m_total = 0; // 初始化静态成员变量时不需要加static


Student::Student(char *name, int age, float score) {

}
void Student::show() {

}


int main()
{
  Student::m_total = 10; // 可以直接由类名访问
  // 栈区
  Student stu("Jack",15,92.5f);
  stu.m_total = 20;   // 也可以直接由对象名访问
  // 堆区
  Student *pstu = new Student("Tom",16,96);
  pstu->m_total = 20;  // 也可以直接由对象名访问

  delete pstu;
  return 0;

}

#include <iostream>
using namespace std;

class Student{
public:
  Student(char *name, int age, float score);
  void show();
public: //声明静态成员函数
  static int getTotal();
  static float getPoints();
private:
  static int m_total; //总人数
  static float m_points; //总成绩
private:
  char *m_name;
  int m_age;
  float m_score;
};

int Student::m_total = 0;
float Student::m_points = 0.0;

Student::Student(char *name, int age, float score): m_name(name), m_age(age), m_score(score){
  m_total++;
  m_points += score;
}
void Student::show(){
  cout<<m_name<<"的年龄是"<<m_age<<"，成绩是"<<m_score<<endl;
}
//定义静态成员函数
int Student::getTotal(){
  return m_total;
}
float Student::getPoints(){
  return m_points;
}

int main(){
  (new Student("小明", 15, 90.6)) -> show();
  (new Student("李磊", 16, 80.5)) -> show();
  (new Student("张华", 16, 99.0)) -> show();
  (new Student("王康", 14, 60.8)) -> show();

  int total = Student::getTotal();
  float points = Student::getPoints();
  cout<<"当前共有"<<total<<"名学生，总成绩是"<<points<<"，平均分是"<<points/total<<endl;

  return 0;
}