我的代码出现以下错误:
PoliceOfficer.cpp(39):警告C4715:“PoliceOfficer::Patrol”:并非所有控制路径都返回值
ParkingTicket.cpp(54):错误C4716:“GetCarInfo”:必须返回值
我已经评论了大部分的警察::巡逻，所以它更容易排除故障。 不知道我做错了什么。 我把我所有的文件都包括了，以防万一
Car.h
#pragma once
#ifndef CAR_H
#define CAR_H
#include <string>
using namespace std;
// Car class contains the information about a car
class Car
{
private:
string make, model, color, licenseNumber;
public:
// Default Constructor
Car();
// Accessors
string getMake();
string getModel();
string getColor();
string getLicense();
// Mutators
void setMake(string);
void setModel(string);
void setColor(string);
void setLicense(string);
// Overload << operator
friend ostream& operator << (ostream& strm, const Car& obj);
};
#endif // CAR_H
Car.cpp
#include "Car.h"
#include <iostream>
#include <string>
using namespace std;
// Default Constructor
Car::Car()
{
make = "None Set";
model = "None Set";
color = "None Set";
licenseNumber = "None Set";
}
// Accessors
string Car::getMake()
{
cout << "Make: " << make;
return make;
}
string Car::getModel()
{
cout << "Model: " << model;
return model;
}
string Car::getColor()
{
cout << "Color: " << color;
return color;
}
string Car::getLicense()
{
cout << "License: " << licenseNumber;
return licenseNumber;
}
// Mutators
void Car::setMake(string ma)
{
make = ma;
}
void Car::setModel(string mo)
{
model = mo;
}
void Car::setColor(string c)
{
color = c;
}
void Car::setLicense(string l)
{
licenseNumber = l;
}
// Overload << operator
// Author note: I'm not sure what I am supposed to be overloading
// this function with.
ostream& operator << (ostream& strm, const Car& obj)
{
return strm;
}
ParkedCar.h
#pragma once
#ifndef PARKEDCAR_H
#define PARKEDCAR_H
#include <iostream>
#include <string>
#include "Car.h"
using namespace std;
// ParkedCar class simulates a parked car. Knows which type of car is parked and
// the number of minutes that the car has been parked
class ParkedCar
{
private:
// Private Members
// class Car;
Car carObject;
string make;
string model;
string color;
string licenseNumber;
int minutesParked;
public:
// Constructors
ParkedCar();
ParkedCar(string ma, string mo, string c, string l, int mp);
// Copy Constructor
ParkedCar(ParkedCar& obj);
// Accessors
int getMinutesParked() const;
string getMake();
string getModel();
string getColor();
string getLicense();
// Mutators
int setMinutesParked(int);
void setMake(string ma);
void setModel(string mo);
void setColor(string c);
void setLicense(string l);
};
#endif // PARKEDCAR_H
ParkedCar.cpp
#include "ParkedCar.h"
#include <iostream>
#include <string>
using namespace std;
ParkedCar::ParkedCar() // Default Constructor
{
minutesParked = 0;
}
// make, model, color, licenseNumber;
ParkedCar::ParkedCar(string ma, string mo, string c, string l, int mp) // Constructor with 5 parameters
{
carObject.setMake(ma);
carObject.setModel(mo);
carObject.setColor(c);
carObject.setLicense(l);
minutesParked = mp;
}
// Copy Constructor
ParkedCar::ParkedCar(ParkedCar& obj)
{
carObject.setMake(obj.make);
carObject.setModel(obj.model);
carObject.setColor(obj.color);
carObject.setLicense(obj.licenseNumber);
minutesParked = obj.minutesParked;
}
// Accessors
string ParkedCar::getMake()
{
return make;
}
string ParkedCar::getModel()
{
return model;
}
string ParkedCar::getColor()
{
return color;
}
string ParkedCar::getLicense()
{
return licenseNumber;
}
int ParkedCar::getMinutesParked() const
{
return minutesParked;
}
// Mutators
void ParkedCar::setMake(string ma)
{
make = ma;
}
void ParkedCar::setModel(string mo)
{
model = mo;
}
void ParkedCar::setColor(string c)
{
color = c;
}
void ParkedCar::setLicense(string l)
{
licenseNumber = l;
}
int ParkedCar::setMinutesParked(int mp)
{
minutesParked = mp;
return 0;
}
ParkingMeter.h
#pragma once
#ifndef PARKINGMETER_H
#define PARKINGMETER_H
#include <iostream>
#include <string>
using namespace std;
class ParkingMeter
{
private:
// Private Members
int minutes; // Minutes purchased for parking
public:
// Constructors
ParkingMeter();
ParkingMeter(int);
// Accessors
int getMinutes();
// Mutators
int setMinutes(int);
};
#endif // PARKINGMETER_H
ParkingMeter.cpp
#include "ParkingMeter.h"
#include <iostream>
#include <string>
using namespace std;
// Default Constructor
ParkingMeter::ParkingMeter()
{
minutes = 0;
}
// Constructor with 1 parameter
ParkingMeter::ParkingMeter(int i)
{
minutes = i;
}
// Accessor
int ParkingMeter::getMinutes()
{
return minutes;
}
// Mutator
int ParkingMeter::setMinutes(int m)
{
minutes = m;
return 0;
}
// Overload << operator
const ostream& operator << (ostream& strm, const ParkingMeter& obj)
{
return strm;
}
PoliceOfficer.h
#include "ParkingMeter.h"
#include <iostream>
#include <string>
using namespace std;
// Default Constructor
ParkingMeter::ParkingMeter()
{
minutes = 0;
}
// Constructor with 1 parameter
ParkingMeter::ParkingMeter(int i)
{
minutes = i;
}
// Accessor
int ParkingMeter::getMinutes()
{
return minutes;
}
// Mutator
int ParkingMeter::setMinutes(int m)
{
minutes = m;
return 0;
}
// Overload << operator
const ostream& operator << (ostream& strm, const ParkingMeter& obj)
{
return strm;
}
PoliceOfficer.cpp
#include "PoliceOfficer.h"
#include <iostream>
#include <string>
using namespace std;
//Default Constructor
PoliceOfficer::PoliceOfficer()
{
ParkingTicket* ticketPtr = nullptr;
officerName = " ";
badgeNumber = " ";
}
// Constructor with 2 elements
PoliceOfficer::PoliceOfficer(string n, string b)
{
officerName = n;
badgeNumber = b;
}
ParkingTicket *PoliceOfficer::patrol(ParkedCar car, ParkingMeter meter)
{
parkedMinutes = car.getMinutesParked();
cout << "Parked Minutes: " << parkedMinutes << endl;
meterMinutes = meter.getMinutes();
cout << "Meter Minutes: " << meterMinutes << endl;
minutes = parkedMinutes - meterMinutes;
cout << "Minutes: " << minutes << endl;
if (minutes <= 0)
{
return nullptr;
}
else
{
ParkingTicket ticket(car, minutes);
};
}
// Accessors
string PoliceOfficer::getOfficerName()
{
return officerName;
}
string PoliceOfficer::getBadgeNumber()
{
return badgeNumber;
}
// Mutators
string PoliceOfficer::setOfficerName(string n)
{
officerName = n;
return 0;
}
string PoliceOfficer::setBadgeNumber(string b)
{
badgeNumber = b;
return 0;
}
// Overload << operator
const ostream& operator << (ostream& out, const PoliceOfficer& obj)
{
out << "Officer: " << &PoliceOfficer::getOfficerName;
out << " (badge #" << &PoliceOfficer::getBadgeNumber;
out << ")" << endl;
return out;
}
ParkingTicket.h
#pragma once
#ifndef PARKINGTICKET_H
#define PARKINGTICKET_H
#include <iostream>
#include <string>
#include "ParkedCar.h"
#include "ParkingMeter.h"
#include "Car.h"
using namespace std;
// ParkingTicket class simulates a parking ticket
// Reports the car information for illegally parked car
// Reports the fine which is $25 for the first hour or part
// of an hour that the car is illegally parked, plus $10
// for every additional hour or part of an hour
class ParkingTicket
{
private:
// Private Members
// class ParkedCar;
double fine; // The calculated parking fine
double* fineptr = &fine; // fine pointer
int minutes; // The minutes illegally parked
const int firstHour = 25; // first hour fine
const int subHours = 10; // subsiquent hour fine
// Car Info
string make, model, color, licenseNumber;
public:
// Constructors
ParkingTicket();
ParkingTicket(ParkedCar car, int meter);
// Accessors
double getFine();
int getMinutes();
// Mutators
double setFine(double);
int setMinutes(int);
// Method
double fineCalc(); // calculate the fine
string GetCarInfo();
// friend const ostream& operator << (ostream&, const ParkingTicket&);
};
const ostream& operator << (ostream&, const ParkingTicket&);
#endif // PARKINGTICKET_H
ParkingTicket.cpp
#include "ParkingTicket.h"
#include <iostream>
#include <string>
using namespace std;
ParkingTicket::ParkingTicket() // Default Constructor
{
double fine = 0;
double* fineptr = &fine;
int minutes = 0;
const int firstHour = 25;
const int subHours = 10;
}
// Constructor with 2 parameters (ParkedCar and an integer)
ParkingTicket::ParkingTicket(ParkedCar car, int min)
{
minutes = min; // illegally parked minutes
cout << "Minutes: " << endl;
ParkingTicket::fineCalc(); // calculate fine
cout << fine;
}
// Accessors
double ParkingTicket::getFine()
{
return fine;
}
int ParkingTicket::getMinutes()
{
return minutes;
}
// Mutators
double ParkingTicket::setFine(double f)
{
fine = f;
return 0;
}
int ParkingTicket::setMinutes(int m)
{
minutes = m;
return 0;
}
string GetCarInfo()
{
&Car::getMake;
//&Car::getModel;
//&Car::getColor;
//&Car::getLicense;
}
// Car information, Time on the meter
double ParkingTicket::fineCalc()
{
fine = 25;
minutes -= 60;
while (minutes >= 60)
{
fine += subHours;
minutes -= 60;
}
if (minutes >= 0)
{
fine += subHours;
}
return fine;
}
// Overload << operator
const ostream& operator << (ostream& out, const ParkingTicket& obj)
{
out << &ParkingTicket::GetCarInfo;
return out;
}
main.cpp
#include <iostream>
#include <string>
#include "ParkedCar.h"
#include "ParkingMeter.h"
#include "ParkingTicket.h"
#include "PoliceOfficer.h"
using namespace std;
int main()
{
ParkingTicket *ticket = nullptr;
ParkedCar car("Volkswagen", "1972", "Red", "147RHZM", 125);
ParkingMeter meter(60);
PoliceOfficer officer("Joe Friday", "4788");
ticket = officer.patrol(car, meter);
if (ticket != nullptr)
{
cout << "we made it this far officer" << endl;
cout << officer;
cout << "we are at the ticket" << endl;
cout << *ticket;
delete ticket;
ticket = nullptr;
}
else
cout << "No crimes were committed.\n";
return 0;
}
您只是在这里错过了一个返回语句:
if (minutes <= 0)
{
return nullptr;
}
else
{
ParkingTicket ticket(car, minutes);
// you must return something. I guess it is return ParkingTicket(...
};
这里也一样:
string GetCarInfo()
{
&Car::getMake;
//&Car::getModel;
//&Car::getColor;
//&Car::getLicense;
}
您将GetCarInfo（）声明为一个字符串，您需要返回一个字符串。
GetCarInfo应该返回一个字符串，但它没有:
string GetCarInfo()
{
&Car::getMake;
}
因此出现了错误。
getCarInfo是ParkingTicket中的一个函数，因此您需要在定义中也指定该函数。 但我真的不确定你想回到这里做什么。 上下文中没有汽车。
也许是这样的？
string ParkingTicket::GetCarInfo()
{
return make; //make is a private member of the class.
}
无论如何，语法&car::GetMake；是一个方法函数指针，指向类car中的一个方法。 方法函数指针有点奇怪，所以如果您是编程新手，可能不是有意要使用它。 如果您打算调用car中的方法getMake，则应该有一个类型为car的对象来调用:
Car car;
car.getMake();
请注意，PoliceOfficer::Patrol中的丢失返回语句只发出警告（与GetCarInfo()中丢失返回的错误相比）。 如果你让函数结束而不返回（任何事情都可能发生！），那将是UB（未定义行为）。 所以这是好的，你正在寻找警告和想要修复他们以及！ 修复方法是只添加return语句:
ParkingTicket PoliceOfficer::patrol(ParkedCar car, ParkingMeter meter)
{
if (minutes <= 0)
{
return nullptr;
}
else
{
return ticket(car, minutes);
};
}
