出现错误提示
.. \ src \ CS20实验2第2部分。cpp：75：38：错误：抽象类类型'CS_Student'的无效new表达式]
基类：
/*
* Student.h
*
* Created on: Jan 23, 2020
* Author: Student
*/
enter code here
#ifndef STUDENT_H_`#define STUDENT_H_
#include <string>
using namespace std;
class Student {
protected:
string *name;
int *age;
public:
Student();
void setName(string s) ;
void setAge(int i);
string getName() const;
int getAge() const;
virtual void print() = 0;
virtual ~Student();
};
#endif /* STUDENT_H_ */
Student.cpp：
/*
* Student.h
*
* Created on: Jan 23, 2020
* Author: Student
*/
#ifndef STUDENT_H_
#define STUDENT_H_
#include <string>
using namespace std;
class Student {
protected:
string *name;
int *age;
public:
Student();
void setName(string s) ;
void setAge(int i);
string getName() const;
int getAge() const;
virtual void print() = 0;
virtual ~Student();
};
#endif /* STUDENT_H_ */
派生类：
/*
* CSStudent.cpp
*
* Created on: Jan 23, 2020
* Author: Student
*/
#include <string>
#include <iostream>
#include "CS_Student.h"
#include "Student.h"
using namespace std;
CS_Student::CS_Student() {
favProgLang = new string;
cout << "CS_Student object created!" << endl;
}
void CS_Student::setFavProgLang(string s){
*favProgLang = s;
}
string CS_Student::getFavProgLang() const{
return *favProgLang;
}
void CS_Student::print() const{
cout << "\nPRINT REPORT FOR CS_STUDENT OBJECT" << endl;
cout << "\tName: " << *name << endl;
cout << "\tAge: " << *age << endl;
cout << "\tFavorite Programming Language: " << *favProgLang << endl;
}
CS_Student::~CS_Student() {
delete favProgLang;
cout << "CS_Student object destroyed!" << endl;
}
/*
void setFavProgLang(string s);
string getFavProgLang() const;
void print() const;
*/
衍生标题：
/*
* CSStudent.h
*
* Created on: Jan 23, 2020
* Author: Student
*/
#ifndef CS_STUDENT_H_
#define CS_STUDENT_H_
#include <string>
#include "Student.h"
#include <iostream>
using namespace std;
class CS_Student: public Student {
private:
string *favProgLang;
public:
CS_Student();
void setFavProgLang(string s);
string getFavProgLang() const;
void print() const;
virtual ~CS_Student();
};
#endif /* CS_STUDENT_H_ */
主要：
#include "CS_Student.h"
#include "EnglishStudent.h"
/*******************************************************************************
* Function Prototypes
*******************************************************************************/
#include <iostream>
#include <string>
using namespace std;
void getInput(CS_Student**, const int);
void getInput(EnglishStudent**, const int);
void display(Student*);
/*******************************************************************************
* int main()
* Starting point of the program.
*
* Output:
* An integer to signal to the OS the exit code.
*******************************************************************************/
int main() {
// variables
const int CS_SIZE = 2;
const int ENG_SIZE = 3;
CS_Student* csArray[CS_SIZE];
EnglishStudent* engArray[ENG_SIZE];
// call the getInput method overloads for both arrays
getInput(csArray, CS_SIZE);
getInput(engArray, ENG_SIZE);
// call the polymorphic display function for both arrays
for (int i = 0; i < CS_SIZE; i++) {
display(csArray[i]);
}
for (int i = 0; i < ENG_SIZE; i++) {
display(engArray[i]);
}
// release the dynamic memory for objects inside both arrays
for (int i = 0; i < CS_SIZE; i++) {
delete csArray[i];
}
for (int i = 0; i < ENG_SIZE; i++) {
delete engArray[i];
}
// terminate
return 0;
}
/*******************************************************************************
* void getInput(CS_Student** objArray, const int SIZE)
* Use a for loop to create dynamic CS student objects. Prompt the user for the
* name/age/favorite programming language of each CS student. Store the
* information in the dynamic object.
*
* Inputs:
* objArray - a double-pointer that should be treated as an array of dynamic
* CS student objects
* SIZE - a constant integer that represents the size of the array
*******************************************************************************/
void getInput(CS_Student** objArray, const int SIZE) {
// variables
string name = "", fpl = "";
int age = 0;
// for each CS student
for (int i = 0; i < SIZE; i++) {
// create the dynamic CS student object
objArray[i] = new CS_Student();
// prompt and store the name of the current CS student
cout << "Enter the name for CS student #" << i + 1 << ": ";
getline(cin, name);
// prompt and store for the age of the current CS student
cout << "Enter the age for CS student #" << i + 1 << ": ";
cin >> age;
// need to ignore the newline in the buffer
cin.ignore();
// prompt and store the favorite programming language of the current
// CS student
cout << "Enter the favorite programming language for CS student #"
<< i + 1 << ": ";
getline(cin, fpl);
// add the data to the dynamic object
objArray[i]->setName(name);
objArray[i]->setAge(age);
objArray[i]->setFavProgLang(fpl);
}
}
/*******************************************************************************
* void getInput(EnglishStudent** objArray, const int SIZE)
* Use a for loop to create dynamic English student objects. Prompt the user
* for the name/age/favorite book of each English student. Store the
* information in the dynamic object.
*
* Inputs:
* objArray - a double-pointer that should be treated as an array of dynamic
* English student objects
* SIZE - a constant integer that represents the size of the array
*******************************************************************************/
void getInput(EnglishStudent** objArray, const int SIZE) {
// variables
string name = "", book = "";
int age = 0;
// for each English student
for (int i = 0; i < SIZE; i++) {
// create the dynamic English student object
objArray[i] = new EnglishStudent();
// prompt and store the name of the current English student
cout << "Enter the name for English student #" << i + 1 << ": ";
getline(cin, name);
// prompt and store for the age of the current English student
cout << "Enter the age for English student #" << i + 1 << ": ";
cin >> age;
// need to ignore the newline in the buffer
cin.ignore();
// prompt and store the favorite book of the current English student
cout << "Enter the favorite book for English student #"
<< i + 1 << ": ";
getline(cin, book);
// add the data to the dynamic object
objArray[i]->setName(name);
objArray[i]->setAge(age);
objArray[i]->setFavBook(book);
}
}
/*******************************************************************************
* void display(Student* obj)
* A polymorphic function. Simply calls the (virtual) print method. Used to
* demonstrate polymorphism. Any derived class that inherits from the Student
* class can be used as an argument.
*
* Input:
* obj - a pointer to an object that inherits from the Student class
*******************************************************************************/
void display(Student* obj) {
obj->print();
}
真的很困惑，因为学生是我的基类，具有纯虚函数virtual void print() = 0;并且在CS_Student中被覆盖void CS_Student::print() const我也尝试将此处的CS_Student更改为Student，并且它没有任何改变。在此先感谢
基础：virtual void print() = 0;
派生：void print() const;
派生版本中的额外const会更改派生函数的签名，实例变量this为const，因此它与基本函数不匹配。基数必须为const或派生值不得为const。更喜欢前者。
例如
virtual void print() = 0;
成为
virtual void print() const= 0;
在C ++和最新的标准修订版中，您可以通过使用override关键字标记希望覆盖基类函数的所有函数来更轻松地捕获此错误。这几乎总是导致更容易理解的错误消息。
例如
void print() const override;
结果（在我的工具链上）
error: 'void CS_Student::print() const' marked 'override', but does not override
void print() const override;