如何在不使用数字作为触发来结束循环的情况下结束加数的while循环

Question

I'm trying to write a program that adds numbers continuously until the user enters a word or something to stop the program. Currently, I used -9999 but what if the user want to add -9999? I'm new at this can someone help please.

float Addition()
{
    Sum = 0;
    cout << "Please enter number you wish to add:" << endl;
    cin >> num;

    while(num != -9999)
    {
        Sum += num;
        cout << "Sum is:" << Sum << endl;
        cout << "Please enter number or enter -9999 to exit" << endl;
        cin >> num;

        if(!cin.good())
        {
            throw exception();
        }                   
    }
}

Answer 1

The usual approach is to change the loop to:

while (cin >> num)

This will continue to prompt for input until ean nd of file condition which, depending on your operating system, is signaled by typing either Ctrl-D or Ctrl-Z .