Class holding vector of classes - c++

Question

I am learning OOP in C++ so I tried to practice a little. I want to create a "database" (using objects) of class and its students. I created a class for a student. Each have a name and age.
class Ziak {
public:
Ziak(int,string);
int getAge() {
return age;
}
string getName() {
return name;
}
private:
int age;
string name;
};
Ziak::Ziak(int age,string name) {
this->age=age;
this->name=name;
}
And I created a class of a Classroom , each is represented by its name , teacher and students ( vector of objects )
class Trieda {
public:
Trieda(string,string);
void fillStudents() {
while(1) {
int age;
string name;
cout << "Name: ";
getline(cin,name);
cout << "Age: ";
cin >> age;
Ziak newStudent(age,name);
n.push_back(newStudent);
if(cin.eof()) {
break;
}
}
}
string getTeacher() {
return ucitel;
}
string getNamesOfStudents() {
for(unsigned i = 0; i < n.size(); i++) {
cout << "hey " << n[i].getName() << endl;
}
}
protected:
vector<Ziak> n;
string nazov;
string ucitel;
};
Trieda::Trieda(string nazov,string ucitel) {
this->nazov = nazov;
this->ucitel = ucitel;
}
and I am just calling its methods in main:
int main() {
Trieda newClass("4A","Ms Foster");
newClass.fillStudents();
newClass.getNamesOfStudents();
return 0;
}
My problem here is the method fillStudents() output starts pretty nice:
Name: // insert name
Age : // insert age
but the second iteration looks worse:
Name:Age: // insert something
and the third iteration is an infinite loop printing Name:Age: till the end of the world.
I tried to just use cin >> name instead of getline, e.g:
void fillStudents() {
while(1) {
int age;
string name;
cout << "Name: ";
cin >> name;
/*getline(cin,name);*/
cout << "Age: ";
cin >> age;
if(cin.eof()) {
break;
} else {
Ziak newStudent(age,name);
n.push_back(newStudent);
}
cin.clear();
}
}
It works. But it works like this:
Name: // insert name
Age : // insert age
// it works till the last one when i press ctrl+Z as eof (currently on windows)
// it outputs Age: Hey + first name ....
Hey name 2 // and so on , then it crashes
What causes this? I suspect it could be something with buffer not being cleared but I tried cin.clear() and it happened too. How can I implement it with getline (I wanted full name as name input e.g John Wicked).
I am trying to figure it out but I'm just a beginner with C++ so my knowledge is limited.
Edit
I fixed it using cin.get() as advised from question posted in comments, now my function looks like this:
void fillStudents() {
while(1) {
int age;
string name;
cout << "Name: ";
//cin >> name;
getline(cin,name);
cout << "Age: ";
cin >> age;
if(cin.eof()) {
break;
} else {
if(cin.fail()) {
cout<< "chyba ";
break;
}
Ziak newStudent(age,name);
n.push_back(newStudent);
}
cin.get();
}
}
What still makes me uncomfortable is the output with cout. It produces this:
Name: John
Age: 15
Name: Lia
Age: 25
Name: Age: hey John
hey Lia
The Name: Age: still gets printed after eof, I tried to put cin.eof() test at the start of the while loop but it messed up all of the output. How can I modify the code without it showing the cout after eof?

Answer 1

You need to check for eof (Ctrl+z(^Z)) after name has been entered and after age has been entered. If you enter Ctrl+z for name then the eofbit flag will be set on cin but not caught until after outputting Age:. The reason it doesn't pause for age input is because:
The extraction also stops if the end of file is reached in [the istream] or if some other error occurs during the input operation. - C++ Reference - getline
Note: The istream in the quote above is cin in your code.
Your code should resemble:
// above code removed for brevity
cout << "Name: ";
getline(cin,name);
if(cin.eof()) {
break;
}
cout << "Age: ";
cin >> age;
if(cin.eof()) {
break;
} else {
// below code removed for brevity
Output:
Tested on Windows with CodeBlocks and GCC.
Name: ^Z[Enter]
Process returned 0 (0x0) execution time : 1.685 s
Press any key to continue.
Name: John
Age: ^Z [Enter]
Process returned 0 (0x0) execution time : 1.685 s
Press any key to continue.