C++ While 循环不重新分配字符串值

问：

我创建了一个程序来计算提供的字符串中的元音数量。它正确地计算元音，并在用户提供“y”或“Y”时重复。但是，当它重复时，它会自动将 “” 分配给我尝试使用的 C 字符串。

int main()
{
    //Creating repeating decision
    char answer = 'y';

    while ((answer == 'y') || (answer == 'Y'))
    {

        //declaring our C-String
        char ourString[81] = "Default";

        //Prompting user for a string, storing it as a C-String
        std::cout << "Please enter a string!(Less than 80 characters please.)\n";
        std::cin.getline(ourString, 81);

        //Using a loop to count the amount of vowels
        int ourNum = 0;
        int vowels = 0;

        while (ourString[ourNum] != '\0')
        {
            switch (ourString[ourNum]) {
            case 'a':
            case 'A':
            case 'e':
            case 'E':
            case 'i':
            case 'I':
            case 'o':
            case 'O':
            case 'u':
            case 'U':
            case 'y':
            case 'Y':
                vowels++;
                ourNum++;
                break;
            default:
                ourNum++;
                break;
            }

        }
        std::cout << "The numbers of vowels in: \"" << ourString << "\" is " << vowels << "!\n";
        std::cout << "Do again? Please enter \"Y\" to repeat, or any other character to escape.";
        std::cin >> answer;

    }

}

任何方向将不胜感激。谢谢！