This is the code I wrote, total beginner
#include <iostream>
#include <cstring>
using namespace std;
class Person
{
public:
string ID;
string name;
string surname;
string department;
string email;
public:
//get and set functions for ID, Name, Surname, Department, Email properties
string getID()
{
return this->ID;
};
void setID(string _ID)
{
this->ID = _ID;
};
string getName()
{
return this->name;
};
void setName(string _name)
{
this->name = _name;
};
string getSurname()
{
return this->surname;
};
void setSurname(string _surname)
{
this->surname = _surname;
};
string getDepartment()
{
return this->department;
};
void setDepartment(string _department)
{
this->department = _department;
};
string getEmail()
{
return this->email;
};
void setEmail(string _email)
{
this->email = _email;
};
};
//inherit Student class from Person class
class Student :public Person
{
private:
int student_counter = 0;
public:
//constructor
Student()
{
};
Student(string id, string Name, string Surname, string Department, string Email)
{
setID(id);
setName(Name);
setSurname(Surname);
setDepartment(Department);
setEmail(Email);
}
//student add
void addStudent(string id, string Name, string Surname, string Department, string Email)
{
if (student_counter >= 100)
{
cout << "cant add more students";
}
else
{
Student _S[100]
Student newS;
newS.setID(id);
newS.setName(Name);
newS.setSurname(Surname);
newS.setDepartment(Department);
newS.setEmail(Email);
_S[student_counter] = newS;
student_counter ;
}
}
//display students
void display()
{
for (int i = 0; i < student_counter; i )
{
cout << _S[i].getID() << " - ";
}
}
};
};
int
main()
{
Student stu;
stu.addStudent("ST123456", "Ege", "Inan", "CS", "ege @ gmail.com");
stu.display();
}
The problem is here
//inherit Student class from Person class
class Student :public Person
{
private:
int student_counter = 0;
public:
//constructor
Student()
{
};
Student(string id, string Name, string Surname, string Department, string Email)
{
setID(id);
setName(Name);
setSurname(Surname);
setDepartment(Department);
setEmail(Email);
}
//student add
void addStudent(string id, string Name, string Surname, string Department, string Email)
{
if (student_counter >= 100)
{
cout << "cant add more students";
}
else
{
Student _S[100];
Student newS;
newS.setID(id);
newS.setName(Name);
newS.setSurname(Surname);
newS.setDepartment(Department);
newS.setEmail(Email);
_S[student_counter] = newS;
student_counter ;
}
}
//display students
void display()
{
for (int i = 0; i < student_counter; i )
{
cout << _S[i].getID() << " - ";
}
}
};
};
The error message I get is this:
main.cpp:106:9: error: ‘_S’ was not declared in this scope
106 | cout<<_S[i].getID()<<" - ";
| ^~
I tried moving the definition of Student _S to the private part of student class like this:
class Student :public Person
{
private:
int student_counter = 0;
Student _S[100];
public:
//constructor
Student()
{
};
Student(string id, string Name, string Surname, string Department, string Email)
{
setID(id);
setName(Name);
setSurname(Surname);
setDepartment(Department);
setEmail(Email);
}
//student add
void addStudent(string id, string Name, string Surname, string Department, string Email)
{
if (student_counter >= 100)
{
cout << "cant add more students";
}
else
{
Student newS;
newS.setID(id);
newS.setName(Name);
newS.setSurname(Surname);
newS.setDepartment(Department);
newS.setEmail(Email);
_S[student_counter] = newS;
student_counter ;
}
}
//display students
void display()
{
for (int i = 0; i < student_counter; i )
{
cout << _S[i].getID() << " - ";
}
}
};
};
But then I got this:
65 | Student _S[100];
| ^~
main.cpp:61:7: note: definition of ‘class Student’ is not complete until the closing brace
61 | class Student:public Person
| ^~~~~~~
What would be the best way of handling this? where to define the array to get the program to run as intended?
CodePudding user response：
In the first code, _S is a local variable inside of addStudent(), so display() can't access it.
Your second code is better, in that display() can now access _S. But a Student object can't hold any data members that are also Student objects, you would end up with an endless recursive allocation.
To accomplish what you want, you need to make _S, student_counter, addStudent(), and display() be static members of the Student class, eg:
class Student :public Person
{
private:
static int student_counter;
static Student _S[100];
public:
//constructor
Student()
{
};
Student(string id, string Name, string Surname, string Department, string Email)
{
setID(id);
setName(Name);
setSurname(Surname);
setDepartment(Department);
setEmail(Email);
}
//student add
static void addStudent(string id, string Name, string Surname, string Department, string Email)
{
if (student_counter >= 100)
{
cout << "cant add more students";
}
else
{
Student newS;
newS.setID(id);
newS.setName(Name);
newS.setSurname(Surname);
newS.setDepartment(Department);
newS.setEmail(Email);
_S[student_counter] = newS;
student_counter ;
}
}
//display students
static void display()
{
for (int i = 0; i < student_counter; i )
{
cout << _S[i].getID() << " - ";
}
}
};
int Student::student_counter = 0;
Student Student::_S[100];
int main()
{
Student::addStudent("ST123456", "Ege", "Inan", "CS", "ege @ gmail.com");
Student::display();
}