对象间共享变量和操作共享变量的成员函数前面加static

/* Online C++ Compiler and Editor */
#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:
//    static int m_total;  //静态成员变量


private:
    char *m_name;
    int m_age;
    float m_score;
};

void Student::show()
{
    
    cout << m_total << endl; 
    
}

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

int Student::m_total  = 1;

int main()
{
   //Student obj("a", 1, 1.3f);
   
   //obj.show();
   
   cout << Student::m_total << endl; 
   
   cout << sizeof(Student) << endl;
   cout << "Hello World" << endl; 
   
   return 0;
   
}