Thread: Noob programmer getting "double free or corruption (out)" error

I'm a fresh programmer.

So this is my first OOP program that I'm writing for a class. I'm getting a "double free or corruption (out)" error.

The program that I am writing basically makes Student objects and stores info about them like test scores(in an array), their name and ID. My teacher told us all the public and private member funtions so I started there. I wrote the basic structure and then through a bunch of cout statements to I could get it navigate through program properly. I'm slowly working it up and adding stuff little by little until I get it to do everything I need it to do.

I commented out all the class members that I haven't gotten to yet.
Have mercy on my sad sad code....

Code:

#include<iostream>
#include<string>

using namespace std;

class Student
{
private:
    string name;
    int id;
    int * test;
    int num;
//    void makeArray()
//    {
//        cout << "making array...\n";
//
//    }
public:
    Student()
    {
        cout << "creating student...1\n";
        setName("None");
        setID(10);

    }

    Student(int n)
    {
        cout << "creating student...2\n";
        setName("None");
        setID(10);
    }

    Student(string nm, int i, int n)
    {
        cout << "creating student...3\n";
        setName(nm);
        setID(i);
    }

    void setName(string nm)
    {
        cout << "Setting name...\n";
        cout << "The Name: ";
        cin >> name;

    }

    void setID(int i)
    {
        cout << "setting ID...\n";
        num = 3;
        //makeArray();

    }

//    void setScore(int i, int s)
//    {
//
//    }

    string getName() const
    {
        cout << name << endl;

    }

    int getID() const
    {
        cout << id << endl;
    }

    void showScore()
    {
        cout << "showing score";

    }

    void display()
    {
        cout << "showing display";

    }

//    ~Student()
//    {
//
//    }

};

int main()
{
    cout << "In main\n";
    Student studentA,
        studentB(4),
        studentC("Joe",40,5);
    cout << "Before showing names...\n";
    studentA.getName();
    cout << "after studentA.\n";
    studentB.getName();
    cout << "after studentB.\n";
    studentC.getName();
    cout << "after studentC.\n";
    return 0;

}

The error happens at this getName call in main: "studentA.getName();"

Where am I going wrong?

This may or may not be the cause of your problem, but I notice that your getName member function is declared as returning a string object, but you did not actually return a string object. You made a similiar omission for your getID member function. (EDIT: by the way, if you compile at a suitably high warning level, your compiler is likely to warn you about these potential problems.)

Also, the nm parameter of your setName member function is not used.

Originally Posted by std10093

Change getName and getId prototypes to return void.

Actually, I think that you should keep them as-is. Rather, they should actually return the name and id, which is then printed (or otherwise used) by the caller. If you want to print them instead, then it would make sense to rename them to printName and printId respectively, and hence using void as the return type would be sensible.

Originally Posted by std10093

In the constructor with the three arguments, just assign the name with the argument.Do not call setName.

I think the setName call is okay. If you wanted to get rid of it, then you might as well use the initialiser list instead of assignment.