C++ 有 typeid 关键字，可以在动态运行时得到一个类的类别。

我利用 static 变量尝试判断一个对象的类别

测试代码如下:

#include <bits/stdc++.h>
#define rep( i , j , n ) for ( int i = int(j) ; i < int(n) ; ++i )
#define dew( i , j , n ) for ( int i = int(n-1) ; i > int(j) ; --i )
#define _PATH __FILE__ , __LINE__
typedef std::pair < int , int > P ;
using std::cin ;
using std::cout ;
using std::endl ;
using std::string ;
enum class Type {
    Object , Student , Teacher , Course
} ;

class Object {
public:
    const static Type type = Type::Object ;
public:
    static const char* get_type_name () {
        return "Object" ;
    }
} ;

class Student : public Object {
public:
    const static Type type = Type::Student ;
public:
    static const char* get_type_name () {
        return "Student" ;
    }
} ;

class Teacher : public Object {
public:
    const static Type type = Type::Teacher ;
public:
    static const char* get_type_name () {
        return "Teacher" ;
    }
} ;

class Course : public Object {
public:
    const static Type type = Type::Course ;
public:
    static const char* get_type_name () {
        return "Course" ;
    }
} ;

void Judge ( const Type type ) {
    switch ( type ) {
        case Type::Object : {
            cout << "是一个 Object 类" << endl ;
            break ;
        }
        case Type::Student : {
            cout << "是一个 Student 类" << endl ;
            break ;
        }
        case Type::Teacher : {
            cout << "是一个 Teacher 类" << endl ;
            break ;
        }
        case Type::Course : {
            cout << "是一个 Course 类" << endl ;
            break ;
        }
    }
}

int main () {
    Object One ;
    Judge ( One.type ) ;
    Student Two ;
    Judge ( Two.type ) ;
    Teacher Three ;
    Judge ( Three.type ) ;
    Course Four ;
    Judge ( Four.type ) ;

    cout << "\nOne   类别的名字是  " << One.get_type_name () ;
    cout << "\nTwo   类别的名字是  " << Two.get_type_name () ;
    cout << "\nThree 类别的名字是  " << Three.get_type_name () ;
    cout << "\nFour  类别的名字是  " << Four.get_type_name () ;

    if ( One.type == Student::type ) 
        cout << "\n\nOne  和类型 Student  匹配" ;
    else
        cout << "\n\nOne  和类型 Student  不匹配\n" ;

    Teacher* Five = new Teacher ;
    if ( Five->type == Teacher::type )
        cout << "\nTeacher* Five 和类型 Teacher 匹配\n" ;
    else 
        cout << "\nTeacher* Five 和类型 Teacher 不匹配\n" ;

    Object* Six = new Teacher () ;
    cout << "\nObject* Six.name  = " << Six->get_type_name () << endl ;
    if ( Six->type == Teacher::type )
        cout << "\nObject* Six 和类型 Teacher 匹配\n" ;
    else 
        cout << "\nObject* Six 和类型 Teacher 不匹配\n" ;

    cout << "\nObject* Six.name  = " << (*Six).get_type_name () << endl ;
    // Object* Six-> 和 (*Six). 都只能取到 Object 的部分
    if ( (*Six).type == Teacher::type )
        cout << "\nObject Six 和类型 Teacher 匹配\n" ;
    else 
        cout << "\nObject Six 和类型 Teacher 不匹配\n" ;

    return 0 ;
}