Handling of references and pointers in C++ function overloading and rewriting

When a function is overloaded, a reference or pointer is passed, and all functions must use the same type of data. When a function is rewritten, for reference member functions, the subclass function must refer to the same type of variable; for pointing to member functions, the subclass function must point to the same type of variable.

Handling of references and pointers in C function overloading and rewriting

Function overloading

Function overloading is allowed in the same role Create multiple functions within a domain with the same name but different parameter lists. For references and pointers, we need to pay attention to the following points:

• When passing references, all functions must refer to the same type of data:

  void print(const int& num);
  void print(const double& d);

• When passing pointers, all functions must point to the same type of data:

  void print(int* num);
  void print(double* d);

Function override

Function override Is to implement a function in the parent class with the same name and parameter list in the subclass. For references and pointers, we need to pay attention:

• For reference member functions, the subclass function must refer to the same type of variable:

  class Parent {
  public:
    void setAge(const int& age);
  };
  
  class Child : public Parent {
  public:
    void setAge(const int& age) override;  // 同一类型引用
  };

• For pointing to member functions, subclass functions must point to variables of the same type:

  class Parent {
  public:
    int* getPtr();
  };
  
  class Child : public Parent {
  public:
    int* getPtr() override;   // 同一类型指针
  };

Practical case

Assume we have A Person class that represents a person's age and name. There are two member functions in this class: setAge(const int& age) and setName(const string& name).

We create a subclass Employee, inherit from the Person class, and override the setAge function to set the age to Add 5 to it before age.

class Person {
public:
    void setAge(const int& age);
    void setName(const string& name);
};

class Employee : public Person {
public:
    void setAge(const int& age) override;  // 重写setAge函数
};

// Employee 类中的 setAge 函数
void Employee::setAge(const int& age) {
    Person::setAge(age + 5);  // 调用父类setAge函数
}

Now, we can create an Employee object and use the overridden setAge function:

Employee emp;
emp.setAge(20);  // 实际设置为 25

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