求和

    int sum = 0, val = 1;
    while (val<=10)
    {
        sum += val;
     val++;
    }
    cout << "Sum of 1 to 10 inclusive is " << sum << endl;
    return 0;

    int length, i, sum = 0;
    cout << "输入一个数，从一开始相加 " << endl;
    cin >> length;
    for (int i = 0; i <= length; i++)
    {
        sum += i;
    }
    cout << sum << endl;