Reference to local variable returned

Question

I am trying to implement a character selection method, for a text based game and i know that it will not work the way i did it, because i am returning a refernce to an object with a lifetime limited to the scope of the method call. I have also tried to implement the method without referencing the Fighter parent class and returning a child class (Samus and Ryu) based on the players character choice, but then i would get this error: invalid abstract return type 'Fighter'.

Fighter characterSelection(int player,bool checkForBot, Fighter &fig)
{
int input;
string newName;

if(checkForBot)
{
    input = (rand()%2)+1;
}
else{
    cout << "Please choose your Fighter player"<<player<<": \n1. Samus\n2. Ryu\n";
    input = readInput<int>();
}
if(input == 1)
{
    Samus sam;
    if(checkForBot)
    {
        cout << "Bot selected Samus!";
    }
    else{
        cout << "Player"<<player<<" selected Samus!\nDo you wish to change your fighters name?\n1.Yes\n2.No\n";
        input = readInput<int>();
        if(input == 1)
        {
            cout << "new Name: ";
            newName = readInput<string>();
            changeName(newName,sam);
        }
    }
    return sam;
}
else if(input == 2)
{
    Ryu ry;
    if(checkForBot)
    {
        cout << "Bot selected Ryu!";
    }
    else {
        cout << "Player"<<player<<" selected Ryu!\nDo you wish to change your fighters name?\n1.Yes\n2.No\n";
        input = readInput<int>();
        if(input == 1)
        {
            cout << "new Name: ";
            newName = readInput<string>();
            changeName(newName,ry);
        }
    }
    return ry;
 }
}

After having chosen one character and the end of the function call, the destructor of the object is called upon, thus making the reference linked to a non-existing object.

int main()
{
int input;
string newName;
bool checkForBot;
int player=1;
while(true)
{
    cout << "1. PVP \n2. PVE\n";
    input = readInput<int>();
    if(input == 1)
    {
       checkForBot = false;
        //Character Selection
        Fighter &fig1 = characterSelection(player,checkForBot,fig1);
        player++;
        Fighter &fig2 = characterSelection(player,checkForBot,fig2);
        //Battle
        fightPVP(fig1, fig2);

    }
    else if(input ==2)
    {
        //Character Selection
        Fighter &fig1 = characterSelection(player,checkForBot,fig1);
        checkForBot = true;
        Fighter &bot = characterSelection(player,checkForBot,bot);
        //Battle
        fightPVE(fig1, bot);
    }
}
return 0;
}

Is there any other way i could solve this problem, instead of referencing the parent class and then creating the child in the function call?

Answer 1

In this:

Fighter &fig1 = characterSelection(player,checkForBot,fig1);

you are making a reference to a local object copy returned by the function.

Returning a parent object has also the issue of object slicing; you should have that in account.

If that's not a problem, however, you can add a copy constructor to the class and just remove the reference when declaring the receiving variable:

Fighter fig1 = characterSelection(player,checkForBot,fig1);

If your object is not suited to copy, other way is to new the object in characterSelection and return a pointer (or better, shared pointer) of the base class.