成功创建c ++类和对象[重复]

Posted 2023-02-17

【中文标题】成功创建c ++类和对象[重复]

【英文标题】：Creating c++ classes and objects successfully [duplicate]

【发布时间】：2019-11-19 21:32:16

【问题描述】：

我正在从头开始用 C++ 编写应用程序，从一开始我就在定义类、为其创建构造函数以及创建类的实例/对象时遇到了麻烦。我在编写代码时会检查代码以避免错误，但是当我尝试创建类的对象时，我的问题就开始了。我会感谢任何人的帮助。也可能是我以错误的方式在 C++ 中创建类、构造函数等。我将不胜感激修改我的代码和任何建议。 当我运行下面的代码时，我收到错误消息“运算符

#include <string>

using namespace std;

class Person


public:
    Person(string firstName, string lastName, string nationality, string occupation);

    Person();

    void setFirstName(string firstName)
    
        this->firstName = firstName;
    

    void getFirstName()
    
        cout << firstName;
    

    void setLastName(string lastName)
    
        this->lastName = lastName;

    

    void getLastName()
        cout << lastName;
    

    void setNationality(string nationality)
    
        this->nationality = nationality;
    

    void getNationality()
    
        cout << nationality;
    

    void setOccupation(string occupation)
    

        this->occupation = occupation;
    

    void getOccupation()
    
        cout << occupation;
    

public:
    string firstName;
    string lastName;
    string nationality;
    string occupation;

;

int main()

    Person p3;
    p3.setFirstName("Larra");
    cout << p3.getFirstName();
    cout << p3.firstName;
        return 0;

我已将代码更改为以下代码。但是我现在收到的错误消息是'collect2:error:Id returned 1 exit status'。请问我该如何解决？

#include <iostream>
#include <string>

using namespace std;

class Person


public:
    Person(string firstName, string lastName, string nationality, string occupation);

    Person();

    void setFirstName(string firstName)
    
        this->firstName = firstName;
    

    string getFirstName()
    
        return firstName;
    

    void setLastName(string lastName)
    
        this->lastName = lastName;

    

    string getLastName()
        return lastName;
    

    void setNationality(string nationality)
    
        this->nationality = nationality;
    

    string getNationality()
    
        return nationality;
    

    void setOccupation(string occupation)
    

        this->occupation = occupation;
    

    string getOccupation()
    
        return occupation;
    

public:
    string firstName;
    string lastName;
    string nationality;
    string occupation;
;

int main()

    Person p3;
    p3.setFirstName("Larra");
    cout << p3.firstName;
        return 0;
```


******************************************************************
I HAVE FINALLY GOT IT WORKING. THANKS TO EVERYONE THAT HELPED. I  commented out two lines around the start of the program and it started working. You can see the working version below.
******************************************************************

#include <iostream>
#include <string>

using namespace std;

class Person


public:
    string firstName;
    string lastName;
    string nationality;
    string occupation;

public:
    //Person(string firstName, string lastName, string nationality, string occupation);

    //Person();

    void setFirstName(string firstName)
    
        this->firstName = firstName;
    

    string getFirstName()
    
        return firstName;
    

    void setLastName(string lastName)
    
        this->lastName = lastName;

    

    string getLastName()
        return lastName;
    

    void setNationality(string nationality)
    
        this->nationality = nationality;
    

    string getNationality()
    
        return nationality;
    

    void setOccupation(string occupation)
    

        this->occupation = occupation;
    

    string getOccupation()
    
        return occupation;
    

;

int main()

    Person p3;
    p3.setFirstName("Larra");
    p3.setLastName("Marrudds");
    cout << p3.firstName << '\n' << p3.lastName <<endl;
        return 0;

【问题讨论】：

哪些行有错误？

投票结束是一个错字。你忘了#include <iostream>

错误来自 cout

getFirstName 没有返回任何内容，实际上没有任何 get 方法。

@ayedecoder 你有getFirstName() 返回void。它应该是字符串。 void 不是您可以打印的。

【参考方案1】：

重载类的构造函数和<< ostream 的运算符。这将允许您使用运算符

Person() = default;

然后有一个替代的集合函数或另一个构造函数。

对于你的成员变量国籍和职业，你的参数也是一样的。它们必须不同。

#include <iostream>
#include <ostream>
#include <string>

using namespace std;

class Person


 public:
  string firstName;
  string lastName;
  string Nationality;
  string Occupation;

  Person() = default; // Overload the constructor

  Person(string firstName, string lastName, string n, string o)
  
    // You could use this also,
    this->firstName = firstName;
    this->lastName = lastName;
    this->Nationality = n;
    this->Occupation= o;
    // etc...
  ;



  void setFirstName(string firstName)
  
    this->firstName = firstName;
  

  void getFirstName()
  
    cout << firstName;
  

  void setLastName(string lastName)
  
    this->lastName = lastName;

  

  void getLastName()
    cout << lastName;
  

  void setNationality(string nationality)
  
    this->Nationality = nationality;
  

  void getNationality()
  
    cout << Nationality;
  

  void setOccupation(string occupation)
  

    this->Occupation = occupation;
  

  void getOccupation()
  
    cout << Occupation;
  

  // Overload operator
  friend std::ostream& operator<<(std::ostream &os, Person &p)
  
    os << p.firstName << " " << p.lastName << " " << p.Nationality << " " << p.Occupation;
    return os;
  
;

int main()

  Person p3;

  Person p4("Jack", "Hanson", "Nationality", "Ocupation");

  p3.setFirstName("Larra");

  p3.setLastName ("Hanson");

  cout << p3 << endl;

  cout << p4 << endl;

  return 0;

【讨论】：

谢谢大家。我现在已经解决了这个问题，我已经用工作代码编辑了我的原始帖子。