如何在C ++中通過引用復制對象？

Question

我有以下情況。 那就是我想要做的：

std::vector < Shape > shapesArr;
Shape *shape = new Shape();
shape->someParam = someValue;
shapesArr.push_back( Shape );

// ...

Shape *shape2 = new Shape();
shape2 = shapesArr[ 0 ]; // <-- here I need a copy of that object to shapeA

delete[] shapesArr;
delete shape2; // <-- error, because it has already freed. It would be nice if I had a copy of shapesArr[ 0 ] in my shape2

如何正確地將該對象復制到shape2？ 我需要該對象的兩個副本，這些副本將分別存儲在shapesArr [0]和shape2中。

Answer 1

您可以使用Shape *shape2 = new Shape(shapesArr[0]); 創建副本。

您的代碼中有兩個錯誤：

第一：

std::vector < Shape > shapesArr;
Shape *shape = new Shape();
shape->someParam = someValue;
// you should push *shape, because Shape is just the class name
// and shape is a Shape* type pointer
// you can shapesArr.push_back( *shape );
shapesArr.push_back( Shape );

其次，您不能刪除矢量，因為您沒有新建矢量，如果要擦除矢量中的所有元素，請使用shapesArr.clear()或shapesArr.erase(shapesArr.begin(),shapesArr.end());