CODEWITHSUNDEEP
c++doublecin
GraiL
GraiL

Reputation: 23

C++ detect empty value

If the sales manager does not enter any sales amounts, the program should display the “Invalid Input” message.

    double sales = 0.0;
    double totSales = 0.0;
    double aveSales = 0.0;
    int ctr = 0;
    
    cout << "Please enter sales amount: \n";

    for (int x = 0; x >= 0; x++){
        cout << ">>";
        cin >> sales;
        if (sales > 0){
            totSales += sales;
            cout << endl;
        }
        else if (sales == 0){
            cout << "Invalid input.\n\n";
            x = x - 1;
        }
        else{
            ctr = x;
            x = -2;
        }
    }
    aveSales = totSales / ctr;
    cout << "Average Sales: " << aveSales << endl;

I already tried length, size, empty, fail and null. None of them work.

else if (sales == 0 || this where I added the second condition for empty input){
            cout << "Invalid input.\n\n";
            x = x - 1;
        }

Upvotes: 0

Views: 911

Answers (2)

Krishna Kanth Yenumula
Krishna Kanth Yenumula

Reputation: 2567

cin >> sales returns std::istream object.

In C++11 and later standards , std::istream object will be converted to bool, only if we use it in if or while.

You can use : if(cin >> sales) to check for valid input.

References :

  1. Address and return values of cin
  2. What does cin return?

Upvotes: 1

tai
tai

Reputation: 528

I would propose getting the standard input as a std::string and check it for emptiness:

std::string sales;

// ...
getline(std::cin, sales);

if (sales.empty() || 0 == std::stod(sales)) {
  std::cout << "Invalid input!\n";
}
else {
  double salesVal = std::stod(sales);

  // and so forth
}

This will also make sure the entered value is a valid double value.

Upvotes: 0

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