如何在C ++中通过引用复制对象？

Question

我有以下案例。这就是我想要做的事情：

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

如何将该对象正确复制到shape2？我需要该对象的两个副本，它们将分别存储在shapesArr [0]和shape2中。

Answer 1

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

您的代码中有两个错误：

首先：

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，你不能删除矢量，因为你没有新的矢量，如果要删除矢量中的所有元素，请使用shapesArr.clear()或shapesArr.erase(shapesArr.begin(),shapesArr.end());