如何验证输入文件中的.txt数据？ C ++

Question

The goal is to get an Item Name - string - (.txt) and price - double - (.txt) from a .txt. I am required to check this input and make sure it is valid, and if not, return 1, and exit the program. I was able to check to make sure the input file was opened. But I am drawing a blank on how to go about checking the other data. The validation was explained to be done in groups of two (item/price) at a time.

For the string values I just need to make sure the line isn't blank. For the double values I need to make sure they are numeric.

int getData(int& listSize, menuItemType*& menuList, int*& orderList)
{
    //-----Declare inFile
    ifstream inFile;
    string   price, size;

    //-----Open inFile
    inFile.open("Ch9_Ex5Data.txt");

    //-----Check inFile
    if (inFile.is_open())
    {
        //-----Get Amount of Items, Convert to int 
        getline(inFile, size);
        listSize = stoi(size);      <---This needs to be positive int 

        //-----Set Array Size
        menuList  = new menuItemType[listSize];
        orderList = new int[listSize];

        //-----Get Menu
        for (int x = 0; x < listSize; x++)
        {
            //-----Get menuItem
            getline(inFile, menuList[x].menuItem);//-make sure data recieved

            //-----Get menuPrice convert to double
            getline(inFile, price);
            menuList[x].menuPrice = stod(price);//make sure double < 99

            orderList[x] = 0;
        }                      //teacher explained i should validate in 
                                 groups of two
        return 0;
    }
    else
    {
        return 1;
    }
}

//This is the .txt.
8
Plain Egg
1.45
Bacon and Egg
2.45
Muffin
0.99
French Toast
1.99
Fruit Basket
2.49
Cereal
0.69
Coffee
0.50
Tea
0.75

Answer 1

For example, you can create a function that tells you whether a pair of values ​​is valid (when menu != empty and 0 < price < 99 . This function will be called each time each pair is read.

bool validation(const string& menu, const double& price){ 
    if(menu.empty() || price < 0 || price > 99)
        return 1 ;
    else
        return 0 ;
}

This function returns 0 when the pair is correct and 1 otherwise (as you indicated).

Now it is only it necessary to invoke the function every time the new pair of values ​​is created. At the moment one of these is invalid, it will exit the program.

for (int x = 0; x < listSize ; x++)
{
    //-----Get menuItem
    getline(inFile, menuList[x].menuItem);//-make sure data recieved

    //-----Get menuPrice convert to double
    getline(inFile, price);//-make sure data recieved
    menuList[x].menuPrice = atof(price.c_str());//make sure double < 99

    //teacher explained i should validate in groups of two
    if(validation(menuList[x].menuItem, menuList[x].menuPrice))
        return 1 ;

    orderList[x] = 0;
}