Question

enum ShapeType
{
    RECTANGLE = 1,
    CIRCLE,
    TRIANGLE,
    MAX
};

int main()
{

    int n;

    std::cout << "Number of elements : ";
    std::cin >> n;

    std::vector <Shape *> shapes;

    for(int i = 0; i < n; i++)
    {
        std::cout << "What shape do you want to build \n 1) Rectangle\n 2) Circle\n 3) Triangle\n" << std::endl;

        int t;
        // de implementat do while

        std::cin >> t;

        for(ShapeType i = RECTANGLE; i < MAX; i = static_cast<ShapeType>(i+1))
        {
            do
            {
                switch (t)
                {
                case RECTANGLE:
                {
                    int width, height;

                    std::cout << "Width = "; cin >> width;
                    std::cout << "Height = "; cin >> height;

                    Shape *rect = new Rectangle(width, height);
                    shapes.push_back(rect);

                    std::cout << "Rectangle area is: " << rect->getArea() << std::endl;
                    std::cout << "Rectangle perimeter is: " << rect->getPerimeter() << std::endl;
                    rect->draw();

                    break;
                }
                case CIRCLE:
                {
                    double radius;

                    std::cout << "Please give circle radius: "; std::cin >> radius;

                    Shape *circ = new Circle(radius);
                    shapes.push_back(circ);

                    break;
                }
                case TRIANGLE:
                {
                    double l1, l2 ,l3;

                    std::cout << "Side 1: "; std::cin >> l1;
                    std::cout << "Side 2: "; std::cin >> l2;
                    std::cout << "Side 3: "; std::cin >> l3;

                    Shape *tri = new Triangle(l1, l2, l3);
                    shapes.push_back(tri);

                    break;
                }
                default:
                    break;
                }
            }
            while(n > i);
            {
                break;
            }
        }
    }

    return 0;
}

我这里有一个抽象的Shape类和继承它的Rectangle，Circle和Triangle。我想介绍一下＆＃39; n＆＃39;形状的数量，并为它们做一个循环。例如，我选择我要制作3个形状，选择它们的选项出现，选择一个形状然后再重复3次。我有这个任务，我必须使用do while。我有一些便宜的尝试，但我迷路了。有什么建议？

Answer 1

你正在重用内循环中的索引i，导致外循环行为不端。将其更改为另一个变量，例如j，并更改此变量的相关用途。

Answer 2

这只是一个快速解释如何做到这一点。

int n,i=0;  
    cout << "Enter no of elements";
    cin >> n;

    if( n > 0 ){
        do{
            int shapeType;
            cout << "choose type";
            cin >> shapeType;
            switch(shapeType){
                case RECTANGLE:
                    break;
                case CIRCLE:
                    break;
                ...
            }
            ++i;
        }while(i<n);
    }

c ++创建一个数组

2 个答案: