这段代码是怎么实现的深层拷贝？（code在里面）

[崔鹏飞]

class Student : ICloneable
    {
        public string Name;
        public Int32 Age;

        public Student(string name, Int32 age)
        {
            Name = name;
            Age = age;
        }

        public void ShowInfo()
        {
            Console.WriteLine("{0}'s age is {1}", Name, Age);
        }

        public Object Clone()
        {
            //实现浅拷贝
            return MemberwiseClone();
        }
    }

    class Enrollment : ICloneable
    {
        //定义引用类型数据成员
        public List<Student> students = new List<Student>();

        //定义默认构造函数
        public Enrollment()
        {
        }

        //提供实现深拷贝的私有实例创建构造函数
        private Enrollment(List<Student> studentList)
        {
            foreach (Student s in studentList)
            {
                students.Add((Student)s.Clone());
            }
        }

        public void ShowEnrollmentInfo()
        {
            Console.WriteLine("Students enrollment information:");
            foreach (Student s in students)
            {
                Console.WriteLine("{0}'s age is {1}", s.Name, s.Age);
            }
        }

        public object Clone()
        {
            //执行浅拷贝
            //return MemberwiseClone();
            //执行深拷贝
            return new Enrollment(students);
        }
    }

[崔鹏飞]

foreach (Student s in studentList)
            {
                students.Add((Student)s.Clone());
            }

这样就是深拷贝了？
这不是就是把students里面已有的元素再复制一份还是放在students里面吗？？

[gomoku]

就是把studentsstudentList里面已有的元素再复制一份还是放在students里面

[jacklau88]

foreach (Student s in studentList)
{
students.Add((Student)s.Clone());
}

[TengGaoqing]

[Quote=引用 3 楼 jacklau88 的回复:]
foreach (Student s in studentList)
{
students.Add((Student)s.Clone());
}
[/Quote]

[崔鹏飞]

return new Enrollment(students);

[Quote=引用 2 楼 gomoku 的回复:]
就是把studentsstudentList里面已有的元素再复制一份还是放在students里面
[/Quote]但是调用的时候，还是把students传进去了啊......

[崔鹏飞]

是不是这样：

public object Clone()
        {
            return new Enrollment(students);
          //这里传的参数是原来旧对象的students
        }

而

private Enrollment(List<Student> studentList)
        {
            foreach (Student s in studentList)
            {
                students.Add((Student)s.Clone());
                 //在这个私有的构造函数里面写的students是新的实例的students
            }
        }

这样解释对吗？？

[崔鹏飞]

我在六楼的理解对吗？？

[coolshark]

关注~~关注~~ C++影子好重

[hustcyb]

首先来看Student的Clone方法：

        public Object Clone()
        {
            //实现浅拷贝
            return MemberwiseClone();
        }

这里关键是MemberwiseClone()方法，首先它会创建一个新的Student对象，接着为Student创建一个新的string类型的Name字段和int类型的Age字段，然后将原始Student对象中的Name中字符串值和Age的值复制过来。

这里要注意string虽然是引用类型，但是微软对其进行了特殊处理，复制时是复制其值而不是引用。因此上面的代码完全等同于：

        public Object Clone()
        {
            return new Student(Name, Age);
        }

也就是说Student的Clone是深复制而不是浅复制。

[孤剑]

9楼的兄弟说的比较详细了。

我在补充一点，如果还是不理解可以看看 DataTable.Clone() DataTable.Copy() 的差异。
直接从数据上看：
Clone() 后的table2继续保存原有table1的结构(structure)不变;
Copy() 后 table2 里填充的全部是table1 的内容，包括结构和数据（data）

同时，对于 MemberwiseClone() 的最好解释，还是看看MSDN吧》
MemberwiseClone cannot be overridden, and is only accessible through this class or a derived class. Use a class that implements the ICloneable interface if a deep or shallow copy of an object needs to be publicly exposed to users.

A shallow copy creates a new instance of the same type as the original object, and then copies the nonstatic fields of the original object. If the field is a value type, a bit-by-bit copy of the field is performed. If the field is a reference type, the reference is copied but the referred object is not; therefore, the reference in the original object and the reference in the clone point to the same object. In contrast, a deep copy of an object duplicates everything directly or indirectly referenced by the fields in the object.

For example, if X is an Object with references to the objects A and B, and the object A also has a reference to an object M, a shallow copy of X is an object Y, which also has references to objects A and B. In contrast, a deep copy of X is an object Y with direct references to objects C and D, and an indirect reference to object N, where C is a copy of A, D is a copy of B, and N is a copy of M.

[崔鹏飞]

请看一下六楼对吗？[Quote=引用 7 楼 cuipengfei1 的回复:]
我在六楼的理解对吗？？
[/Quote]

[gomoku]

[Quote=引用 7 楼 cuipengfei1 的回复:]
我在六楼的理解对吗？？
[/Quote]
对