在BST中使用C ++使用目标文件的功能

Question

I am making a Binary Search Tree and I have the following function in a .cpp file:

void MovieTree::printMovieInventory(MovieNode* node)
{
    if(node)
    {
        while(node->rightChild && node->leftChild)
        {
            std::cout<<"Movie:"<<node->title<<" "<<node->quantity<<std::endl;
            if(node->rightChild)
            {
                printMovieInventory(node->rightChild);
            }
            if(node->leftChild)
            {
                printMovieInventory(node->leftChild);
            }
        }
    }
    else
    {
        std::cout<<"No movies in list!"<<std::endl;
    }

I am a little unsure as to how I should be referring to this function in my main.cpp file or "driver file". I referred to it in main using this:

            case 3: //message is read in from file
              {
                MovieTree::printMovieInventory(node);
              }

                break;

However, Upon referencing this it just throws an error:

Driver.cpp:37:40: error: cannot call member function 'void MovieTree::printMovieInventory(MovieNode*) without object
MovieTree::printMovieInventory(node);

Not sure what this means.

full main here:

int main(int argc, char **argv)
{
    bool quit = false;
    string s_input;
    int input;

    // loop until the user quits
    while (!quit)
    {
        MovieNode* node = new MovieNode;
        printOptions();

        // read in input, assuming a number comes in
        getline(cin, s_input);
        input = stoi(s_input);

        switch (input)
        {
            // print all nodes
            case 1:     //rebuild network

                break;


                break;

            case 3: //message is read in from file
              {
                MovieTree::printMovieInventory(node);
              }
                break;

            case 4:     // quit
                quit = true;
                cout << "Goodbye!"<< endl;
                break;

            default:    // invalid input
                cout << "Invalid Input" << endl;
                break;
        }
    }

}

Answer 1

You need an instance of MovieTree. Somehwere in your code and above the switch statement, you should add:

MovieTree movieTree;

and then your switch statement will look like this:

case 3: //message is read in from file
                movieTree.printMovieInventory(node);
                break;

Alternatively, if MovieTree has no state (ie. no fields or other functions it depends on) you can mark printMoviewTree as static instead of the code above.