I'm having several problems in developing this program I do not understand why.
1) I can not call the constructor method of the class Terna, with the other two methods manufacturers and pass the values to my interests. Line 21 and 22.
2) Should I create two objects using the 'nuovo' method. In class A should create an object of type B. In class B should I create an object of type A. Ritornandoli. In the new method, and you virtual.
#include <iostream>
#include <stdlib.h>
#include <sstream>
#define DEF 50
using namespace std;
class B;
class Terna{
protected:
int * xyz;
public:
Terna(int _x,int _y,int _z){
xyz = new int[3];
xyz[0] = _x;
xyz[1] = _y;
xyz[2] = _z;
}
Terna(int _x) : Terna(_x, _x, _x){}
Terna(int *_x) : Terna(_x[0],_x[1],_x[2]){}
string toString(){
stringstream t;
t << "[ " << xyz[0] << ", " << xyz[1] << ", " << xyz[2] <<" ]";
return t.str();
}
virtual int m() = 0;
//virtual Terna nuovo(Terna *_t) = 0;
};
class A : public Terna{
public:
A(int _x) : Terna(_x){}
A(int *_x) : Terna(*_x){}
Terna nuovo(Terna *_t){
B * b = new B(m()+xyz[0]);
return b;
}
int m(){
int m = 0;
for(int i=0;i<3;i++)
m += xyz[i];
return m/3;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "A:" + Terna::toString()+" "+s.str();
}
};
class B : public Terna{
public:
B(int _x) : Terna(_x){}
B(int *_x) : Terna(*_x){}
Terna nuovo(Terna *_t){
A * a = new A(m()-xyz[1]-xyz[2]);
return a;
}
int m(){
int max = 0;
for(int i=0;i<3;i++)
if(max<xyz[i])
max = xyz[i];
return max;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "B:" + Terna::toString()+" "+s.str();
}
};
int manin(){
srand(2999888);
Terna * vett[DEF];
int * x = new int[3];
int max = 0;
for(int i=0;i<DEF;i++){
for(int j=0;j<3;j++)
x[j] = rand()%10;
if(rand()%2 == 1) vett[i] = new A(x);
else vett[i] = new B(x);
if(max<vett[i]->m())
max = vett[i]->m();
}
Terna * vett2[DEF/2];
vett2[0] = vett[0];
vett2[1] = vett[DEF];
for(int i=2;i<DEF;i++)
vett2[i] = vett2[i-1]->nuovo(vett2[i-2]);
return 0;
}
C:\Users\angel\Desktop\method\method7.cpp In constructor 'Terna::Terna(int)':
19 35 C:\Users\angel\Desktop\method\method7.cpp [Warning] delegating constructors only available with -std=c++11 or -std=gnu++11 [enabled by default]
C:\Users\angel\Desktop\method\method7.cpp In constructor 'Terna::Terna(int*)':
20 43 C:\Users\angel\Desktop\method\method7.cpp [Warning] delegating constructors only available with -std=c++11 or -std=gnu++11 [enabled by default]
C:\Users\angel\Desktop\method\method7.cpp At global scope:
36 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna A::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] because the following virtual functions are pure within 'Terna':
26 15 C:\Users\angel\Desktop\method\method7.cpp [Note] virtual int Terna::m()
C:\Users\angel\Desktop\method\method7.cpp In member function 'Terna A::nuovo(Terna*)':
36 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna A::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
37 4 C:\Users\angel\Desktop\method\method7.cpp [Error] 'B' was not declared in this scope
37 8 C:\Users\angel\Desktop\method\method7.cpp [Error] 'b' was not declared in this scope
37 16 C:\Users\angel\Desktop\method\method7.cpp [Error] expected type-specifier before 'B'
37 16 C:\Users\angel\Desktop\method\method7.cpp [Error] expected ';' before 'B'
C:\Users\angel\Desktop\method\method7.cpp At global scope:
59 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna B::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
C:\Users\angel\Desktop\method\method7.cpp In member function 'Terna B::nuovo(Terna*)':
59 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna B::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
61 11 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid conversion from 'A*' to 'int' [-fpermissive]
19 3 C:\Users\angel\Desktop\method\method7.cpp [Error] initializing argument 1 of 'Terna::Terna(int)' [-fpermissive]
61 11 C:\Users\angel\Desktop\method\method7.cpp [Error] cannot allocate an object of abstract type 'Terna'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
C:\Users\angel\Desktop\method\method7.cpp In function 'int manin()':
100 26 C:\Users\angel\Desktop\method\method7.cpp [Error] 'class Terna' has no member named 'nuovo'
The delegating constructors seem allowed. You only get a warning about it.
The first error is about the fact that you're returning an instance of Terna. It is not allowed. It is considered an abstract class, since you have a pure virtual (abstract in OO terms) method. You can never have a concrete instance of that.
You should use a pointer to Terna instead.
Also note that your main function is called manin. Typo?
Also note that you're using B before it is 'seen' by the compiler. That's why you're getting the
[Error] 'B' was not declared in this scope
If you do that virtual int m() = 0 inside a class you have a abstract class, Abstract classes cannot be used to instantiate objects, but it can be used to create pointers, so nuovo should return a pointer to Terna.
You cannot create an instance of a Terna class due to virtual int m() = 0;
Modify nuovo to return a pointer, not an object.
and of course, compile with -std=c++11
Also, you cannot use the incomplete class B ... while in A::nuovo() ... (you just forward declare with class B; )
Recommendation: split the file up properly in .h, .cpp and then your problems should be solved.
Thank you so much, I've solved some problems. Now give me the following errors:
C:\Users\angel\Desktop\method\method7.cpp In member function 'virtual Terna* A::nuovo(Terna*)':
49 32 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid use of incomplete type 'class B'
41 7 C:\Users\angel\Desktop\method\method7.cpp [Error] forward declaration of 'class B'
#include <iostream>
#include <stdlib.h>
#include <sstream>
#define DEF 50
using namespace std;
class Terna{
protected:
int * xyz;
public:
/*Terna(int _x,int _y,int _z){
xyz = new int[3];
xyz[0] = _x;
xyz[1] = _y;
xyz[2] = _z;
}*/
Terna(int _x){
xyz = new int[3];
xyz[0] = _x;
xyz[1] = _x;
xyz[2] = _x;
}
Terna(int *_x){
xyz = new int[3];
xyz[0] = _x[0];
xyz[1] = _x[1];
xyz[2] = _x[2];
}
string toString(){
stringstream t;
t << "[ " << xyz[0] << ", " << xyz[1] << ", " << xyz[2] <<" ]";
return t.str();
}
virtual int m() = 0;
virtual Terna * nuovo(Terna *_t) = 0;
};
class B;
class A : public Terna{
public:
A(int _x) : Terna(_x){}
A(int *_x) : Terna(*_x){}
Terna * nuovo(Terna *_t){
Terna * b = new B(m()+xyz[0]);
return b;
}
int m(){
int m = 0;
for(int i=0;i<3;i++)
m += xyz[i];
return m/3;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "A:" + Terna::toString()+" "+s.str();
}
};
class B : public Terna{
public:
B(int _x) : Terna(_x){}
B(int *_x) : Terna(*_x){}
Terna * nuovo(Terna *_t){
Terna * a = new A(m()-xyz[1]-xyz[2]);
return a;
}
int m(){
int max = 0;
for(int i=0;i<3;i++)
if(max<xyz[i])
max = xyz[i];
return max;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "B:" + Terna::toString()+" "+s.str();
}
};
int main(){
srand(2999888);
Terna * vett[DEF];
int * x = new int[3];
int max = 0;
for(int i=0;i<DEF;i++){
for(int j=0;j<3;j++)
x[j] = rand()%10;
if(rand()%2 == 1) vett[i] = new A(x);
else vett[i] = new B(x);
if(max<vett[i]->m())
max = vett[i]->m();
}
cout << max;
Terna * vett2[DEF/2];
vett2[0] = vett[0];
vett2[1] = vett[DEF];
for(int i=2;i<DEF;i++)
vett2[i] = vett2[i-1]->nuovo(vett2[i-2]);
return 0;
}
From class A can not create an object of type B, can you tell me how I could do. Thanks for your help.
I'm having several problems in developing this program I do not understand why.
1) I can not call the constructor method of the class Terna, with the other two methods manufacturers and pass the values to my interests. Line 21 and 22.
2) Should I create two objects using the 'nuovo' method. In class A should create an object of type B. In class B should I create an object of type A. Ritornandoli. In the new method, and you virtual.
#include <iostream>
#include <stdlib.h>
#include <sstream>
#define DEF 50
using namespace std;
class B;
class Terna{
protected:
int * xyz;
public:
Terna(int _x,int _y,int _z){
xyz = new int[3];
xyz[0] = _x;
xyz[1] = _y;
xyz[2] = _z;
}
Terna(int _x) : Terna(_x, _x, _x){}
Terna(int *_x) : Terna(_x[0],_x[1],_x[2]){}
string toString(){
stringstream t;
t << "[ " << xyz[0] << ", " << xyz[1] << ", " << xyz[2] <<" ]";
return t.str();
}
virtual int m() = 0;
//virtual Terna nuovo(Terna *_t) = 0;
};
class A : public Terna{
public:
A(int _x) : Terna(_x){}
A(int *_x) : Terna(*_x){}
Terna nuovo(Terna *_t){
B * b = new B(m()+xyz[0]);
return b;
}
int m(){
int m = 0;
for(int i=0;i<3;i++)
m += xyz[i];
return m/3;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "A:" + Terna::toString()+" "+s.str();
}
};
class B : public Terna{
public:
B(int _x) : Terna(_x){}
B(int *_x) : Terna(*_x){}
Terna nuovo(Terna *_t){
A * a = new A(m()-xyz[1]-xyz[2]);
return a;
}
int m(){
int max = 0;
for(int i=0;i<3;i++)
if(max<xyz[i])
max = xyz[i];
return max;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "B:" + Terna::toString()+" "+s.str();
}
};
int manin(){
srand(2999888);
Terna * vett[DEF];
int * x = new int[3];
int max = 0;
for(int i=0;i<DEF;i++){
for(int j=0;j<3;j++)
x[j] = rand()%10;
if(rand()%2 == 1) vett[i] = new A(x);
else vett[i] = new B(x);
if(max<vett[i]->m())
max = vett[i]->m();
}
Terna * vett2[DEF/2];
vett2[0] = vett[0];
vett2[1] = vett[DEF];
for(int i=2;i<DEF;i++)
vett2[i] = vett2[i-1]->nuovo(vett2[i-2]);
return 0;
}
C:\Users\angel\Desktop\method\method7.cpp In constructor 'Terna::Terna(int)':
19 35 C:\Users\angel\Desktop\method\method7.cpp [Warning] delegating constructors only available with -std=c++11 or -std=gnu++11 [enabled by default]
C:\Users\angel\Desktop\method\method7.cpp In constructor 'Terna::Terna(int*)':
20 43 C:\Users\angel\Desktop\method\method7.cpp [Warning] delegating constructors only available with -std=c++11 or -std=gnu++11 [enabled by default]
C:\Users\angel\Desktop\method\method7.cpp At global scope:
36 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna A::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] because the following virtual functions are pure within 'Terna':
26 15 C:\Users\angel\Desktop\method\method7.cpp [Note] virtual int Terna::m()
C:\Users\angel\Desktop\method\method7.cpp In member function 'Terna A::nuovo(Terna*)':
36 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna A::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
37 4 C:\Users\angel\Desktop\method\method7.cpp [Error] 'B' was not declared in this scope
37 8 C:\Users\angel\Desktop\method\method7.cpp [Error] 'b' was not declared in this scope
37 16 C:\Users\angel\Desktop\method\method7.cpp [Error] expected type-specifier before 'B'
37 16 C:\Users\angel\Desktop\method\method7.cpp [Error] expected ';' before 'B'
C:\Users\angel\Desktop\method\method7.cpp At global scope:
59 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna B::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
C:\Users\angel\Desktop\method\method7.cpp In member function 'Terna B::nuovo(Terna*)':
59 9 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid abstract return type for member function 'Terna B::nuovo(Terna*)'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
61 11 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid conversion from 'A*' to 'int' [-fpermissive]
19 3 C:\Users\angel\Desktop\method\method7.cpp [Error] initializing argument 1 of 'Terna::Terna(int)' [-fpermissive]
61 11 C:\Users\angel\Desktop\method\method7.cpp [Error] cannot allocate an object of abstract type 'Terna'
7 7 C:\Users\angel\Desktop\method\method7.cpp [Note] since type 'Terna' has pure virtual functions
C:\Users\angel\Desktop\method\method7.cpp In function 'int manin()':
100 26 C:\Users\angel\Desktop\method\method7.cpp [Error] 'class Terna' has no member named 'nuovo'
The delegating constructors seem allowed. You only get a warning about it.
The first error is about the fact that you're returning an instance of Terna. It is not allowed. It is considered an abstract class, since you have a pure virtual (abstract in OO terms) method. You can never have a concrete instance of that.
You should use a pointer to Terna instead.
Also note that your main function is called manin. Typo?
Also note that you're using B before it is 'seen' by the compiler. That's why you're getting the
[Error] 'B' was not declared in this scope
If you do that virtual int m() = 0 inside a class you have a abstract class, Abstract classes cannot be used to instantiate objects, but it can be used to create pointers, so nuovo should return a pointer to Terna.
You cannot create an instance of a Terna class due to virtual int m() = 0;
Modify nuovo to return a pointer, not an object.
and of course, compile with -std=c++11
Also, you cannot use the incomplete class B ... while in A::nuovo() ... (you just forward declare with class B; )
Recommendation: split the file up properly in .h, .cpp and then your problems should be solved.
Thank you so much, I've solved some problems. Now give me the following errors:
C:\Users\angel\Desktop\method\method7.cpp In member function 'virtual Terna* A::nuovo(Terna*)':
49 32 C:\Users\angel\Desktop\method\method7.cpp [Error] invalid use of incomplete type 'class B'
41 7 C:\Users\angel\Desktop\method\method7.cpp [Error] forward declaration of 'class B'
#include <iostream>
#include <stdlib.h>
#include <sstream>
#define DEF 50
using namespace std;
class Terna{
protected:
int * xyz;
public:
/*Terna(int _x,int _y,int _z){
xyz = new int[3];
xyz[0] = _x;
xyz[1] = _y;
xyz[2] = _z;
}*/
Terna(int _x){
xyz = new int[3];
xyz[0] = _x;
xyz[1] = _x;
xyz[2] = _x;
}
Terna(int *_x){
xyz = new int[3];
xyz[0] = _x[0];
xyz[1] = _x[1];
xyz[2] = _x[2];
}
string toString(){
stringstream t;
t << "[ " << xyz[0] << ", " << xyz[1] << ", " << xyz[2] <<" ]";
return t.str();
}
virtual int m() = 0;
virtual Terna * nuovo(Terna *_t) = 0;
};
class B;
class A : public Terna{
public:
A(int _x) : Terna(_x){}
A(int *_x) : Terna(*_x){}
Terna * nuovo(Terna *_t){
Terna * b = new B(m()+xyz[0]);
return b;
}
int m(){
int m = 0;
for(int i=0;i<3;i++)
m += xyz[i];
return m/3;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "A:" + Terna::toString()+" "+s.str();
}
};
class B : public Terna{
public:
B(int _x) : Terna(_x){}
B(int *_x) : Terna(*_x){}
Terna * nuovo(Terna *_t){
Terna * a = new A(m()-xyz[1]-xyz[2]);
return a;
}
int m(){
int max = 0;
for(int i=0;i<3;i++)
if(max<xyz[i])
max = xyz[i];
return max;
}
string toString(){
stringstream s;
for(int i=0;i<m();i++)
s << 'x';
return "B:" + Terna::toString()+" "+s.str();
}
};
int main(){
srand(2999888);
Terna * vett[DEF];
int * x = new int[3];
int max = 0;
for(int i=0;i<DEF;i++){
for(int j=0;j<3;j++)
x[j] = rand()%10;
if(rand()%2 == 1) vett[i] = new A(x);
else vett[i] = new B(x);
if(max<vett[i]->m())
max = vett[i]->m();
}
cout << max;
Terna * vett2[DEF/2];
vett2[0] = vett[0];
vett2[1] = vett[DEF];
for(int i=2;i<DEF;i++)
vett2[i] = vett2[i-1]->nuovo(vett2[i-2]);
return 0;
}
From class A can not create an object of type B, can you tell me how I could do. Thanks for your help.
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