CODEWITHSUNDEEP
c++
Aram Omran
Aram Omran

Reputation: 7

data validation in c++ for integer input

void addItem(struct InventoryItem inventory[], int& size){

  cout << "\nEnter the item name: ";
  cin.getline(inventory[size].itemName, 100, '\n');
  while (strlen(inventory[size].itemName) == 0){
        cout << "Invalid item name!" << endl;
        cout << "Enter item name: ";
        cin.getline(inventory[size].itemName, MAX_CHAR, '\n');
      }
  cout << "Enter the item price: ";
  cin >> inventory[size].itemPrice;
  while(!cin || inventory[size].itemPrice < 0){
    cout << "Please enter a valid number: ";
    cin >> inventory[size].itemPrice;
    clear();
  }
  cout << endl;
  size++;
}

My !cin keeps accepting letters as numbers ... any ideas why?

note: I'm new to programming.

Upvotes: 0

Views: 60

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 595402

If operator>> fails to extract a value, it puts the input stream into an error state. You are not clearing that state, or ignoring the bad input that caused it to fail, so operator>> keeps failing.

Try this instead:

void addItem(struct InventoryItem inventory[], int& size){
    do {
        cout << "Enter the item name: ";
        if (cin.getline(inventory[size].itemName, MAX_CHAR, '\n')) {
            if (strlen(inventory[size].itemName) > 0) {
                break;
            }
        }
        else {
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
        }
        cout << "Invalid item name!" << endl;
    } 
    while (true);
    do {
        cout << "Enter the item price: ";
        if (cin >> inventory[size].itemPrice) {
            if (inventory[size].itemPrice >= 0) {
                break;
            }
        }
        else {
            cin.clear();
            cin.ignore(numeric_limits<streamsize>::max(), '\n');
        }
        cout << "Invalid item price!" << endl;
    }
    while (true);
    cout << endl;
    size++;
}

Upvotes: 1

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