Here I am trying to make a subclass of the base class, Airplane. In my main code I haven't tried to use either constructor yet as I am just trying to make sure I can make the subclass Fighter to properly work.
The exact error its giving me is
no matching function for call to 'Airplane:Airplane()'
And says it pertains to this line of code in the Fighter.cpp
Fighter::Fighter(int engi, int seat, string description)
Fighter.cpp
#include "Fighter.h"
Fighter::Fighter(int engin, int seat, string description)
{
fNumEngines = engi;
fNumSeats = seat;
rangeAndSpeedDesc = description;
}
Fighter.h
#include "Airplane.h"
using namespace std;
#ifndef FIGHTER_H_
#define FIGHTER_H_
class Fighter:public Airplane {
private:
int fNumSeats;
int fNumEngines;
string rangeAndSpeedDesc;
}
Airplane.cpp
#include "Airplane.h"
using namespace std;
Airplane::Airplane(int engines, int seats)
{
numSeats = seats;
numEngines = engines;
}
Fighter::Fighter(int engines, int seats, string desc)
{
fNumEngines = engines;
fNumSeats = seats;
rangeSpeed = desc;
}
is equivalent to:
Fighter::Fighter(int engines, int seats, string desc) : Airplane()
{
fNumEngines = engines;
fNumSeats = seats;
rangeSpeed = desc;
}
The base class object is initialized using the default constructor unless another constructor is used to initialize the base class in the initialization list in the constructor implementation.
That's why the compiler cannot compile that function.
You need to:
Add a default constructor to Airplane, or
Use the available constructor of Airplane in the the initialization list.
Looking at your posted code, option 2 is going to work.
Fighter::Fighter(int engines, int seats, string desc) :
Airplane(engines, seats), rangeSpeed(desc)
{
}
Suggestion for cleanup
I don't see why you need the members fNumEngines and fNumSeats in Fighter. The base class already has the members to capture that information. I suggest that you should remove them.
When this constructor is called
Fighter::Fighter(int engines, int seats, string desc)
{
fNumEngines = engines;
fNumSeats = seats;
rangeSpeed = desc;
}
then it calls the default base class constructor. However class Airplane does not have the default constructor. It has a constructor with parameters
Airplane(int, int);
So you need explicitly calll the constructor in the mem-initializer list of the constructor Fighter
For example
Fighter::Fighter(int engines, int seats, string desc) : Airplane( engines, seats )
{
fNumEngines = engines;
fNumSeats = seats;
rangeSpeed = desc;
}
Also it is not clear why the data members of the base class and the derived class are duplicated.
The error contains the information that you need. You havent defined a default constructor for class Airplane. When you construct the child class Fighter in this function:
Fighter(int, int, string);
There will be a call to construct the base class. In your implementation you do not explicitly call the base class constructor:
Airplane::Airplane(int engines, int seats)
And you have no default constructor, so what should the compiler do? It complains.
You wiether need to define a default constructor:
Airplane::Airplane()
Or call an existing constructor in the constructor for fighter:
Fighter::Fighter(int engines, int seats, string desc) : Airplane(engines, seats)
Make sure that if you are calling a base class with a constructor, the name of the constructor is the the same as that of the base class
Related
Within my vehicle base class, I have a private member variable, string type (for type of vehicle, ie car, motorbike, tricycle, etc).
#pragma once
using namespace std;
#include <string>
#include <iostream>
class vehicle {
public:
vehicle(string reg, string make, string model, int age, string type);
virtual ~vehicle() = default;
virtual double costPerDay() = 0;
protected:
int age;
int perDayCostCap(int costPD);
double penceToPounds(int pence);
private:
const string type;
string const reg, make, model;
};
One of the derived classes, bike, has a numberOfWheels variable which is to be passed into its constructor. I want to initialize the base class constructor with type bicycle or tricycle depending on the numberOfWheels.
I can not figure out how to achieve this, seeing as the base class constructor has to be initialized before the function body of the child class.
The following shows what I would like to achieve (though, I know this is not possible):
bike::bike(int engineCC, int numOfWheels, string reg, string make, string model, int age)
:engineCC(engineCC), numOfWheels(numOfWheels) {
string tricOrBic = (numOfWheels == 2) ? "bicicle" : "tricicle";
vehicle:reg=reg, make=make, model=model, age=age, type=tricOrBic;
};
Like this?
bike::bike(int engineCC, int numOfWheels, string reg, string make, string model, int age)
: vehicle(reg, make, model, age, numOfWheels == 2 ? "bicycle" : "tricycle")
, engineCC(engineCC)
, numOfWheels(numOfWheels)
{
}
This is normal programming, maybe you had some problem I'm not seeing.
I'm having difficulties in defining a constructor for a class that inherits the properties of another class
class Transportation {
public:
int ID;
string company;
string vehicleOperator;
Transportation(int,string,string) {
}
};
class SeaTransport: public Transportation {
public:
int portNumber;
SeaTransport(int)::Transportation(int,string,string) {
}
};
I'm having issues with line 18 (SeaTransport(int)::Transportation(int,string,string)).
The error I receive occurs at the pont where I declare Transportation.
As seen in the code, a class Transportation is the body class and class SeaTransport inherits the properies of Transportation.
Transportation::Transportation(int, std::string, std::string)
+2 overloads
type name is not allowed
This error occurs at the int
typedef std::__cxx11::basic_string std::string
type name is not allowed
and this final error occurs at both string variables.
It seems you mix together scoping and a constructor initializer list.
The double-colon operator :: is for scope, while a constructor followed by a single colon and a list of initializations is an initializer list.
You must declare the SeaTransport constructor to take all the arguments, including those for the parent class (assuming you want to pass them on to the base constructor):
SeaTransport(int port, int id, string company, string operator);
Then in the definition (implementation) of the constructor you "call" the parent constructor in the constructor initializer list:
SeaTransport(int port, int id, string company, string oper)
: Transport(id, company, oper), // "Call" the parent class constructor
portNumber(port) // Initialize the own members
{
}
As Mr Some Programmer Dude said, you've a Scope problem in your code,
I will try to answer for your second question which is, how to add featured variables on your constructor.
Same as what you did for the port attribute.
You can define before all your Attribute which is boatNumber as int boadNumber = 0 then, you'll overload your
constructor with boatNumber(num) after the initializer operator and int num before the initializer operator.
class Transportation {
public:
int ID;
string company;
string vehicleOperator;
Transportation(int,string,string) {
}
~Transportation(){}
};
class SeaTransport: public Transportation {
public:
int portNumber;
int boatNumber;
SeaTransport(int num, int port, int id, string company, string oper)
:Transportation(id, company, oper), boatNumber(num),portNumber(port) {}
~SeaTransport(){}
};
But, if you want to get things more specific, you can create another class which is derived from SeaTransport
And then you'll define the number of your boat and more other details, if you want.
I'll draw you an instance of it :
class Boat: public SeaTransport {
public:
int boatNumber;
Boat(int bNum,int num, int port, int id, string company, string oper):
SeaTransport( num, port, id, company, oper),boatNumber(bNum){}
~Boat(){}
};
I have checked the class inheritance syntax and I'm pretty sure I don’t have a mistake ? did anything slip away from me ?
class person
{
public:
int personid;
string personname;
string personadress;
person( int apersonid, string apersonname, string apersonadress )//constructor
{
personid=apersonid;
personname=apersonname;
personadress=apersonadress;
}
int getpersonid()
{
return personid;
}
string getpersonname()
{
return personname;
}
string getpersonadress()
{
return personadress;
}
};
class employee: public person
{
public:
int commission;
employee(int _commission, int apersonid, string apersonname, string apersonaddress) : person(apersonid, apersonname, apersonaddress)
{
commission= _commission;
}
int getcommission()
{
return commission;
}
};
The error I'm getting is
Error 1 error C2512: 'person' : no appropriate default constructor
available
I suspect your problem is that your base class doesn't define a default constructor (with 0 arguments). Instead you have a constructor with multiple arguments.
person( int apersonid, string apersonname, string apersonadress )//constructor
{
personid=apersonid;
personname=apersonname;
personadress=apersonadress;
}
Your employee class inherits from person but it's constructor only takes one argument and does not initialize the base class using it's constructor.
employee( int _commission )
{
commission= _commission;
}
This is an issue b/c when you create an instance of the employee, it's trying to call the person class constructor as well. Since you don't have a default constructor (again, no arguments), you will need to explicitly call the person constructor in the employee constructor.
You have two options.
First, Modify the person constructor to take no arguments
person()
If you use this method, your signature for your employee class won't have to change.
Or you can Modify the employee constructor to take all the arguments the person constructor expects:
class employee: public person
{
public:
int commission;
employee(int _commision, int apersonid, string apersonname, string apersonadress ) : person(apersonId, apersonname, apersonadress)
{
commission = _commission;
}
int getcommission()
{
return commission;
}
};
In the constructor, the code after the colon (:) is a call to the person constructor using the arguments specified (apersonid, apersonname, apersonadress).
The employee constructor then assigns the value of _commission since it's scope is only relevant within the employee class.
Does that make sense?
In C++, if constructors are explicitly defined for a class, but they are all non-default, the compiler will not implicitly define a default constructor, leading to a situation where the class does not have a default constructor. You have defined a non default constructor in your class, this one :
person( int apersonid, string apersonname, string apersonadress )
So you need to define one default constructor yourself. E.g.
person() {}
Keep in mind, that in this case, when you construct an object of employee class the default constructor of person would be called. If that is not desired you need to call the non-default constructor of person in the constructor of employee.
Looked at similar threads and this doesn't show up. Basically I want chef to inherit the functions and data from employee (base class) but i'm having issues with the constructor for the derived class. I'm getting the error: no matching function for call to 'Employee::Employee()' Could someone show me how to declare my constructors for this derived class and my future derived classes for this program. Tried a bunch of things and can't seem to get it working.
class Employee
{
public:
Employee(int theempID, string thefirstName, string thelastName, char theempClass, int thesalary)
{
this->empID = theempID;
this->firstName = thefirstName;
this->lastName = thelastName;
this->empClass = theempClass;
this->salary = thesalary;
};
protected:
int empID;
string firstName;
string lastName;
char empClass;
int salary;
};
class Chef : public Employee
{
public:
Chef(int theempID, string thefirstName, string thelastName, char theempClass, int thesalary, string theempCuisine) : Employee() {}
{
this->empID = theempID;
this->firstName = thefirstName;
this->lastName = thelastName;
this->empClass = theempClass;
this->salary = thesalary;
this->empCuisine = theempCuisine;
};
string getCuisine()
{
return empCuisine;
}
protected:
string empCuisine;
};
#endif // EMPLOYEE
Employee() is trying to default construct an Employee but there is no default constructor for Employee. Instead, construct it with the parameters your constructor it expects.
The Chef constructor should look like this:
Chef(int theempID, string thefirstName, string thelastName, char theempClass, int thesalary, string theempCuisine) :
Employee(theempID, thefirstName, thelastName, theempClass, thesalary), empCuisine(theempCuisine)
{}
Note the body of the constructor is empty. The Employee base class and the member variable are initialized in the initialization list. No assignment necessary in the body. You should also change the base class constructor so it uses initialization instead of assignment.
I am trying the derived class example from TCPL.
Manager is kind of employee with additional info of level. I kept getting the error:
no matching function for call to employee::employee()
in the constructor of manager::manager()
All members of employee are public and accessible. What is wrong with the manager constructor?
#include <iostream>
#include <string>
using namespace std;
class employee{
public:
enum type {M,E};
type hier;
string id;
employee(string idd):hier(E){id=idd;};
};
class manager: public employee{
public:
int level;
manager(string idd, int lv){hier=employee::M; id=idd;level=lv;};
};
void print(employee *x){
if(x->hier == employee::E){
cout<<"I am employee with id "<<x->id<<endl;
}
else{
cout<<"I am manager with id "<<x->id<<endl;
manager* y=static_cast<manager *>(x);
cout<<"My level is "<<y->level<<endl;
}
}
int main(){
employee t("334");
manager u("223", 2);
print(&t);
print(&u);
}
Second version
The previous version was bad in terms of encapsulation
This is the new version
#include <iostream>
using namespace std;
enum type {M, E};
class employee{
string id;
type hier;
public:
employee(string idd, type hi=E):hier(hi),id(idd){}
string whatid(){return id;}
type whattype(){return hier;}
};
class manager: public employee{
int level;
public:
manager(string idd, int lv):employee(idd,M),level(lv){}
int whatlv(){return level;}
};
Instead of directly accessing the private member of employee and manager, I made members private and use a function to access them.
#include <iostream>
#include <string>
#include "manager_employee.h"
using namespace std;
void print(employee *x){
if(x->whattype() == E){
cout<<"I am employee with id "<<x->whatid()<<endl;
}
else{
cout<<"I am manager with id "<<x->whatid()<<endl;
manager *y=(manager *)x;
// manager* y=static_cast<manager *>(x);
cout<<"My level is "<<y->whatlv()<<endl;
}
}
int main(){
employee t("334", E);
manager u("223", 2);
print(&t);
print(&u);
}
By declaring a constructor in employee, you remove its default constructor; so you can't create one without specifying the ID.
This means that any derived classes will need to provide the ID to the base-class constructor:
manager(string idd, int lv) : employee(idd) {hier=employee::M; level=lv;}
// ^^^^^^^^^^^^^
For consistency, you might like to initialise level in the initialiser list rather than the constructor body; and it might make more sense to initialise hier to the correct value via another parameter in the employee constructor, rather than giving it a default value then overwriting it:
employee(string idd, type hier = E) : hier(hier), id(idd) {}
manager(string idd, int lv) : employee(idd, M), level(lv) {}
If you have any explicit constructor for a class, the default constructor goes out of existence.
So for that reason, when you initialize an object of the derived class, it tries to initialize the base class members as well. And as you have not given a constructor taking no arguments, this error is thrown.
Either define a default constructor for employee or try calling the base class constructor as:
manager(string idd, int lv):employee(idd){//your code}
Manager constructor should call base class ctor in its initialization list:
manager(string idd, int lv) : employee(idd) {hier=employee::M; id=idd;level=lv;}
Also consider using initlization list for other members in your classes.