对c++编译错误感到困惑

我完全糊涂了。我在另一个论坛(cplusplus)早些时候发布了这个代码，并得到了帮助，但我不明白为什么编译器给了我这个错误，当我问那里没有回应，所以我希望有人能在这里更详细地解释它。

错误:

Person .cpp:在构造函数' Person::Person(QString) '中:person.cpp:12:16:错误:没有匹配的函数调用' Position::Position() ': m_Name(名字)

从错误中指向的行下面的代码中可以看到- person.cpp:12:16 -不是" ' Position::Position() ': m_Name(名字)。

这是建议的解决方案(#2有效):

你没有指定应该使用什么构造函数来构造m_Position，所以编译器假设你想使用默认构造函数(不带参数的构造函数)。问题是Position没有默认构造函数，所以你会得到这个错误。

有两种方法可以解决这个问题。

1. 为Position添加一个默认值
2. 在Person构造函数中指定你想要使用一个现有的构造函数来构造m_Position。

人:人(QString名称): m_Name(名称),m_Position("123"、"abc"){

}

这就是我仍然困惑的地方为什么编译器会在那个文件中指向那行错误;我想，为什么需要构造函数呢?我假设它到达了那个点，然后停止并读取文件，直到它在setPosition()中看到对Position和Employer的引用，然后停止并打印错误。

但如果是这种情况，那么我仍然不明白为什么它需要这个特定的构造函数，而不是我尝试的其他两个构造函数(默认没有参数，cstor有一个参数)。当你(其他论坛)指出

"specify what constructor should be used to construct m_Position"

我想我在某个地方读到编译器会在飞行中创建一个默认的复制构造函数，这就是我期望在setPosition() (Position和Employer被引用的地方)中发生的事情，因为现在，我只是试图让这个机制发挥作用，然后我将在稍后充实小细节。

所以这就是我的问题:为什么编译器这样做?

这是原始代码(或多或少)。

person.cpp ===========================================

// Person.cpp
// pn Mar03-2014
#include <QString>
#include <QTextStream>
//#include "position.h"
#include "person.h"
//#include "employer.h"
Person::Person(QString name)
  : m_Name(name)
{
}
QString Person::toString()
{
  QString buffer;
  QTextStream bufStr(&buffer);
  bufStr << "Person Name: " << m_Name << endl;
  //buffer = "Person Name: " + m_Name + "n";
  return buffer;
}
void Person::setPosition(Employer newC, Position newP)
{
  m_Position = newP;
  m_Employer = newC;
}

person.h =============================================

#ifndef _PERSON_H_ 
#define _PERSON_H_  
#include <QString>
#include "employer.h"
#include "position.h"
//class Employer;
//class Position;
class Person
{
  public:
    Person(QString name);
    void setPosition(Employer newC, Position newP);
    QString toString();
  private:
    QString m_Name;
    bool m_Employed;
    Position m_Position;
    Employer m_Employer;
};
#endif

position.h ===========================================

#ifndef _POSITION_H_ 
#define _POSITION_H_  
#include <QString>
//class Employer;
//class Person;
class Position
{
  public:
    Position(QString name, QString description);
    QString toString();
  private:
    QString m_Name;
    QString m_Description;
};
#endif

position.cpp =========================================

// Position.cpp
// pn Mar03-2014
#include <QString>
#include <QTextStream>
#include "position.h"
//#include "person.h"
//#include "employer.h"
Position::Position(QString name, QString description)
  : m_Name(name), m_Description(description)
{
}
QString Position::toString()
{
  QString buffer;
  QTextStream bufStr(&buffer);
  bufStr << "Position Name: " << m_Name << endl;
  bufStr << "Position Description: " << m_Description << endl;
  //buffer = "Position Name: " + m_Name + "n";
  //return buffer.toStdString();
  return buffer;
}

employer.h ===========================================

// employer.h
// pn mar08-2014
#ifndef _EMPLOYER_H_ 
#define _EMPLOYER_H_  
#include <QString>
//using namespace std;
//class Person;
//class Position;

class Employer
{
  public:
    Employer(QString name, QString market);
    // bool hire(Person& newHire, Position pos);
    QString toString();
  private:
    QString m_Name;
    QString m_Market;
};
#endif

employer.cpp ==========================================

// employer.cpp
// pn Mar05-2014
#include <QString>
#include <QTextStream>
#include "position.h"
#include "person.h"
#include "employer.h"
Employer::Employer(QString name, QString market)
  : m_Name(name), m_Market(market) {}
QString Employer::toString()
{
  QString buffer;
  QTextStream bufStr(&buffer);
  bufStr << "Employer Name: " << m_Name << endl;
  bufStr << "Employer Market: " << m_Market << endl;
  //buffer = "Person Name: " + m_Name + "n";
  //return buffer.toStdString();
  return buffer;  //QString
}
/*
bool Employer::hire(Person& newHire, Position pos)
{
  return true; 
}
*/

work.cpp(主要 ) ======================================

// work.cpp
// pn mar05-2014
#include <QString>
#include <QTextStream>
#include <iostream>
#include "person.h"
#include "employer.h"
#include "position.h"
using namespace std;
int main()
{
  QString name;
  QString company;
  QString location;
  Person phil("Bozo");
  Employer sst("SST", "Speed");
  Position posture("Standing", "Not Sitting");
  //QTextStream qts();
  //qts << phil.toString();
  name = phil.toString();
  cout << name.toStdString();
  company = sst.toString();
  cout << company.toStdString();
  location = posture.toString();
  cout << location.toStdString();
  return 0;
}

其他错误 =======================================

person.cpp:12:16: note: candidates are:
In file included from person.h:6:0,
                 from person.cpp:7:
position.h:14:5: note: Position::Position(QString, QString)
     Position(QString name, QString description);
     ^
position.h:14:5: note:   candidate expects 2 arguments, 0 provided
position.h:9:7: note: Position::Position(const Position&)
 class Position
       ^
position.h:9:7: note:   candidate expects 1 argument, 0 provided
person.cpp:12:16: error: no matching function for call to ‘Employer::Employer()’
   : m_Name(name)
                ^
person.cpp:12:16: note: candidates are:
In file included from person.h:5:0,
                 from person.cpp:7:
employer.h:19:5: note: Employer::Employer(QString, QString)
     Employer(QString name, QString market);
     ^
employer.h:19:5: note:   candidate expects 2 arguments, 0 provided
employer.h:14:7: note: Employer::Employer(const Employer&)
 class Employer
       ^
employer.h:14:7: note:   candidate expects 1 argument, 0 provided
make: *** [person.o] Error 1

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