C++ :: How To Check Which Variable Has No Value

I am writing a console program for a class. I have satisfied the assignment, but I want to clear up what is mostly a cosmetic problem. The program prints a form to the console and places the cursor at a location on the form where the user inputs data. The problem occurs when the user presses the enter key without entering data. The cursor goes to the beginning of the next line. If the user enters data after this, the program functions correctly. I want to know how I can reposition the cursor if the user enters no data.

This is the code that reads one of the values:

Code:

void getHousing(HANDLE screen, MonthlyBudget &inputBudget) {
placeCursor(screen, HOUSING_ROW, ACTUAL_COL);
cin >> inputBudget.housing;
while (!validateEntry(screen, inputBudget.housing)) {
placeCursor(screen, HOUSING_ROW, ACTUAL_COL);
cout << SEVEN_SPACES << endl;
placeCursor(screen, HOUSING_ROW, ACTUAL_COL);
cin >> inputBudget.housing;
}
}

validateEntry checks that the entered value is >= 0 SEVEN_SPACES is a string of seven spaces to cover up the previous entry.