How to split strings and pass them to class vectors from file-CodePudding

For my university class in programming we have been working on Object Oriented Programming (OOP) and are currently working on a group project. The project is to create a cash register that holds items with their names, amounts, and prices. As well as have a way to track the coins given by the user then determine the coin denomination. These are supposed to be done in different classes and involve objects.

My question is regarding the inventory manager that I am coding. The inventory manager is supposed to take the "data.txt" file and read it into the appropriate vectors. Currently I have a vector for the item name, price, amount, and then the itemList vector which holds a string of all 3 to print to the user for readability.

Here is a snippet from the data file:

20 1.99 Potato Chips
10 5.99 Ibuprofen
4 1.42 Candy
55 3.10 Coffee
12 3.25 Hummus
12 4.55 Guacamole 
7 0.80 Baklava
45 1.50 Chocolate Chip Cookies

My question is, how do I split the line up so that I can pass the amount (first number) to the appropriate vector, pass the price to the appropriate vector, then pass the name to the appropriate vector. Essentially splitting each line into 3 parts. The part that is the most difficult to me is how the names of the items can be 1 word, 2 words, or even 3 words. Making it difficult to predict how many spaces the name will have, which caused a lot of my attempts to not work.

I found a working solution though I'm worried it's incorrect or inefficient and I'm curious in knowing the best way to do this. Thank you so much ahead of time and I will post the class definition and the method I'm working in down below.

< The stream object is inFile>

class inventoryManager
{
    private:
        double total, change, choice;
        vector <int> amount;
        vector <string> name;
        vector <double> price;
        vector <string> itemList;
    public:
        void fileOpen(fstream& inFile);
        void fillInventory(fstream& inFile);
        void printInventory(fstream& inFile);
};

void inventoryManager::fillInventory(fstream& inFile)
{
    string temp;
    string a, b;
    
    while (!inFile.eof())
    {
        inFile >> a >> b;
        amount.push_back(stoi(a));
        price.push_back(stod(b));
        getline(inFile, temp);
        name.push_back(temp);
        itemList.push_back(temp);
    }
}

Attempted: I tried using the find() function to find each space then use the index to print the estimated indices to each side of the white space to the vectors. Though it was extremely messy and wouldn't work if a different data file was inputted. The idea of the program is to be able to work if a different file is put in, similar format but the amount could be 100, and prices could be more digits. I also tried editing the file directly by adding new lines for each space but ran into the item names with multiple spaces and ultimately didn't work.

CodePudding user response：

You are trying to do too many new things at once. Break the problem into pieces and solve them separately, then combine them. To break the string into pieces you can use find and substr, you just have to be careful and debug until you're sure it's working perfectly:

string s = "45 1.50 Chocolate Chip Cookies";
cout << "s: " << s << endl; // for debugging

size_t first = s.find(' ');
cout << first << endl; // for debugging

string amountString = s.substr(0, first);
cout << amountString << "X" <<  endl; // for debugging

size_t second = s.find(' ', first 1);
cout << second << endl; // for debugging

string priceString = s.substr(first 1,second-first-1);
cout << priceString << "X" << endl; // for debugging

string nameString = s.substr(second 1);
cout << nameString << "X" << endl; // for debugging

The purpose of those X's is to be certain that the substring has no trailing space.

Once you have tackled the problem this way (and handed the result in for a grade), you can advance to tools like stringstream, and you won't have to deal with this grubby index arithmetic any more.