Problem creating an array of "class"
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Ok , so the syntax is not Arr_[i].setChiave(3) but
Arr_[i]->setChiave(3)
as per Greg Utas and your new indication. As I wrote I would say that also the version
anagrafica* Arr_ = new anagrafica[N];
for (int i = 0; i < N; i++)
{
Arr_[i] = anagrafica("ciao", "miao", i*25);
}is working the same. Then I have the further problem of the two methods for setting cifrated name and surname tha have no effects. I see that there is some problem of synchronizations with the replies. But ok syntax has been clarified.
You have declared a number of methods in your header file but you have not added their implementation to the .cpp source. In my sample code above you can see the implementation for the
setChiavemethod. You need to do the same for all the other methods declared in the class. -
You have declared a number of methods in your header file but you have not added their implementation to the .cpp source. In my sample code above you can see the implementation for the
setChiavemethod. You need to do the same for all the other methods declared in the class.I attach the method file .cpp
#include "Anagrafica.h"
#include
#includeusing namespace std;
anagrafica::anagrafica(string name,string surname, int key)
{
nome_cifrato=name;
cognome_cifrato=surname;
chiave_cifratura=key;
}void anagrafica::setNome(string n_)
{
nome_cifrato=n_;
}
void anagrafica::setCognome(string c_)
{
cognome_cifrato=c_;
}string anagrafica::getNome()
{
return nome_cifrato;
}
string anagrafica::getCognome()
{
return cognome_cifrato;
}int anagrafica::getChiave()
{
return chiave_cifratura;
}void anagrafica::setChiave(int c)
{
chiave_cifratura=c;
}void anagrafica::stampa()
{
string nom = nome_cifrato;
string cog = cognome_cifrato;
cout<<" nome cifrato "<I can't understand where is the
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Clarified the syntax problem I resume here. The code works also in this way ::
anagrafica* Arr_ = new anagrafica[N];
for (int i = 0; i < N; i++)
{
Arr_[i] = anagrafica("ciao", "miao", i*25);
}for (int i=0; i>chiave;
file>>n;
file>>c;
Arr_[i].setChiave(chiave);
cod(Arr_[i],n,c,chiave);
}
for (int i=0; iBecause I can see all the Arr_ elements containing instances of the class. But two methods recalled from one other method do not heve effects.
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OK thanks. By the way, may I call a method , example setNome(stringaNome) from within another method? I attach here three methods of the class, the greater calling the two small.
void anagrafica::setNome(string n_)
{
nome_cifrato=n_;
}void anagrafica::setCognome(string c_)
{
cognome_cifrato=c_;
}void anagrafica::codifica(string nome_chiaro, string cognome_chiaro, int chiave)
{
char car;
nome_cifrato = "";
cognome_cifrato = "";
for (int i=0;i setNome(nome_cifrato);
for (int i=0; isetCognome(cognome_cifrato);
}The two lines of code hghlighted have no effects.
Those lines have no effect because the default in C++ is to pass an argument by value. That is, to make a copy of it. If you want to modify the data that is passed to the function, it must be passed by reference; another option is to pass a pointer to the argument. To pass by reference, you append a
&to the argument's type. So, you need to change your two small functions like this:void anagrafica::setNome(string**&** n_)
{
nome_cifrato=n_;
}void anagrafica::setCognome(string**&** c_)
{
cognome_cifrato=c_;
}Robust Services Core | Software Techniques for Lemmings | Articles
The fox knows many things, but the hedgehog knows one big thing. -
I think this thread is getting confused (I certainly am). I suggest you start a new thread and post the actual code that you are now using, and explain what methods do not work.
header
#include
#include
using namespace std;class anagrafica
{
private:string nome_cifrato;
string cognome_cifrato;
int chiave_cifratura;public :
anagrafica(string ="", string ="", int=0); //costruttore
void setNome(string );
void setCognome(string );
string getNome();
string getCognome();
void codifica(string , string , int );
void decodifica();
void setChiave(int);
int getChiave();
void stampa();
};
methods
#include "Anagrafica.h"
#include #include using namespace std;anagrafica::anagrafica(string name,string surname, int key)
{
nome_cifrato=name;
cognome_cifrato=surname;
chiave_cifratura=key;
}void anagrafica::setNome(string n_)
{
nome_cifrato=n_;
}
void anagrafica::setCognome(string c_)
{
cognome_cifrato=c_;
}string anagrafica::getNome()
{
return nome_cifrato;
}
string anagrafica::getCognome()
{
return cognome_cifrato;
}int anagrafica::getChiave()
{
return chiave_cifratura;
}void anagrafica::setChiave(int c)
{
chiave_cifratura=c;
}void anagrafica::stampa()
{
string nom = nome_cifrato;
string cog = cognome_cifrato;
cout<<" nome cifrato "<setNome(nome_cifrato);
for (int i=0; isetCognome(cognome_cifrato);
}void anagrafica::decodifica()
{char car;
string nome_chiaro = "";
string cognome_chiaro = "";
for (int i=0;i -
header
#include
#include
using namespace std;class anagrafica
{
private:string nome_cifrato;
string cognome_cifrato;
int chiave_cifratura;public :
anagrafica(string ="", string ="", int=0); //costruttore
void setNome(string );
void setCognome(string );
string getNome();
string getCognome();
void codifica(string , string , int );
void decodifica();
void setChiave(int);
int getChiave();
void stampa();
};
methods
#include "Anagrafica.h"
#include #include using namespace std;anagrafica::anagrafica(string name,string surname, int key)
{
nome_cifrato=name;
cognome_cifrato=surname;
chiave_cifratura=key;
}void anagrafica::setNome(string n_)
{
nome_cifrato=n_;
}
void anagrafica::setCognome(string c_)
{
cognome_cifrato=c_;
}string anagrafica::getNome()
{
return nome_cifrato;
}
string anagrafica::getCognome()
{
return cognome_cifrato;
}int anagrafica::getChiave()
{
return chiave_cifratura;
}void anagrafica::setChiave(int c)
{
chiave_cifratura=c;
}void anagrafica::stampa()
{
string nom = nome_cifrato;
string cog = cognome_cifrato;
cout<<" nome cifrato "<setNome(nome_cifrato);
for (int i=0; isetCognome(cognome_cifrato);
}void anagrafica::decodifica()
{char car;
string nome_chiaro = "";
string cognome_chiaro = "";
for (int i=0;iYou need to execute that code through the debugger to see exactly what is happening. I tried to reproduce it and it was passing blank parameters in to the method. I suspect that the problem is where you are reading values from the input file. [edit] That method is modifying both variables
nome_cifratoandcognome_cifratoinline, and you then callsetNomeandsetCognome. But you have already modified the names so you do not need to call the setter methods. I think you need to look more closely at the design of this application and remove some of the redundancies. -
Those lines have no effect because the default in C++ is to pass an argument by value. That is, to make a copy of it. If you want to modify the data that is passed to the function, it must be passed by reference; another option is to pass a pointer to the argument. To pass by reference, you append a
&to the argument's type. So, you need to change your two small functions like this:void anagrafica::setNome(string**&** n_)
{
nome_cifrato=n_;
}void anagrafica::setCognome(string**&** c_)
{
cognome_cifrato=c_;
}Robust Services Core | Software Techniques for Lemmings | Articles
The fox knows many things, but the hedgehog knows one big thing. -
You need to execute that code through the debugger to see exactly what is happening. I tried to reproduce it and it was passing blank parameters in to the method. I suspect that the problem is where you are reading values from the input file. [edit] That method is modifying both variables
nome_cifratoandcognome_cifratoinline, and you then callsetNomeandsetCognome. But you have already modified the names so you do not need to call the setter methods. I think you need to look more closely at the design of this application and remove some of the redundancies.Ok you are right saying that
Richard MacCutchan wrote:
That method is modifying both variables nome_cifrato and cognome_cifrato inline, and you then call setNome and setCognome. But you have already modified the names so you do not need to call the setter methods.
I didn't see it, I get confused writing the code, probably I inteded to use local variables to build cifrated name and surname. But problem was in this function within the main
void cod (anagrafica arr,string n, string c,int chiave)
{arr.codifica(n,c,chiave);
}
that i re-arranged this way
void cod (anagrafica &arr,string n, string c,int chiave)
{arr.codifica(n,c,chiave);
}
passing the address to "cod". And about this, I understood the reason (Greg Utas was right about the rules but didn't apply to the real problem because i did not need to change the strings passed to the methods but the instance of the class itself). But now there is another behaviour that confuses me : In a previous version the following method :
void anagrafica::stampa()
{
cout<<" nome cifrato "<I had to modify in this new version :
void anagrafica::stampa()
{
string nom = nome_cifrato;
string cog = cognome_cifrato;
cout<<" nome cifrato "<because in the first version it was just printing nothing. Now it prints correctly. I just tried without a real knowledge behind, only some kind of sensation but I don't understand why it didn't work before and why it works now.
Anyway thanks for all the efforts/suggestions. I am just starting with c++ in order to help my children in their school exercise.
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Ok you are right saying that
Richard MacCutchan wrote:
That method is modifying both variables nome_cifrato and cognome_cifrato inline, and you then call setNome and setCognome. But you have already modified the names so you do not need to call the setter methods.
I didn't see it, I get confused writing the code, probably I inteded to use local variables to build cifrated name and surname. But problem was in this function within the main
void cod (anagrafica arr,string n, string c,int chiave)
{arr.codifica(n,c,chiave);
}
that i re-arranged this way
void cod (anagrafica &arr,string n, string c,int chiave)
{arr.codifica(n,c,chiave);
}
passing the address to "cod". And about this, I understood the reason (Greg Utas was right about the rules but didn't apply to the real problem because i did not need to change the strings passed to the methods but the instance of the class itself). But now there is another behaviour that confuses me : In a previous version the following method :
void anagrafica::stampa()
{
cout<<" nome cifrato "<I had to modify in this new version :
void anagrafica::stampa()
{
string nom = nome_cifrato;
string cog = cognome_cifrato;
cout<<" nome cifrato "<because in the first version it was just printing nothing. Now it prints correctly. I just tried without a real knowledge behind, only some kind of sensation but I don't understand why it didn't work before and why it works now.
Anyway thanks for all the efforts/suggestions. I am just starting with c++ in order to help my children in their school exercise.
Roberto64_Ge wrote:
I am just starting with c++ in order to help my children in their school exercise.
Well, I am sorry to have to say this, but what you have created is not a good example of C++ code for them to follow. The two static methods
codanddecodserve no purpose other than to call the actual methods of theanagraficaclass. So they are totally redundant; you could call thecodificamethod direct frommain. There are a number of other issues that look incorrect to me but I do not have time to teach you C++. -
Roberto64_Ge wrote:
I am just starting with c++ in order to help my children in their school exercise.
Well, I am sorry to have to say this, but what you have created is not a good example of C++ code for them to follow. The two static methods
codanddecodserve no purpose other than to call the actual methods of theanagraficaclass. So they are totally redundant; you could call thecodificamethod direct frommain. There are a number of other issues that look incorrect to me but I do not have time to teach you C++.That was a request (strange to me too. Exercise : implement a function that calls the methods ..., not directly in the main. Could also be that it was some type of cut and paste from other exercises so some error in the exercise definition ). As I said I am starting too so I do what I can and for that reason I am writing here otherwise why should I do this (to ask a forum)? Then I think that everyone is doing something makes mistakes some for distraction (some I did here) and some for poor knowledge (and also here). But going straight to my last question is there an explanation? Regards
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That was a request (strange to me too. Exercise : implement a function that calls the methods ..., not directly in the main. Could also be that it was some type of cut and paste from other exercises so some error in the exercise definition ). As I said I am starting too so I do what I can and for that reason I am writing here otherwise why should I do this (to ask a forum)? Then I think that everyone is doing something makes mistakes some for distraction (some I did here) and some for poor knowledge (and also here). But going straight to my last question is there an explanation? Regards
I have no idea where that question came from or what it actually says. But I would assume that if you want an explanation then the place where you found it is the best place to ask. The forums here are more for help in diagnosing and fixing specific problems. There are other sites that offer well written tutorials, such as Learn C++ – Skill up with our free tutorials[^] and C++ Tutorial[^].
