C / C ++ topic - deep and shallow copy copy

Topic: Please tell us what is the deep and shallow copy copy? And implementation code to differentiate them.

【answer】

If a class have the resources, when the object of this class of objects that occur during replication occurs, the process can be called a deep copy, if there is a resource objects but does not copy the resource is shallow copy during the copying process.

[A]

Shallow copy follows:

class Test
{
public:
         Test(int temp)
         {
        p=temp;
         }
         Test(Test &c_t)//自定义的拷贝构造函数
         {
         cout<<"进入copy构造函数"<<endl;
         p=c_t.p1;//复制过程的核心语句
         }
public:
       int p1;
};

int main()
{

         Test a(99);
         Test b=a;
         cout<<b.p1;
         cin.get();
return 0;

}

Deep copy is also known as a deep copy of the object dynamic member, not just a simple assignment, but rather to re-allocate dynamic space.

Deep copy sample code is as follows:

class Rect
{
public:
         Rect()//构造函数，p指向堆中分配空间
         {
         p=new int(100);
         }
         Rect(const Rect &r)
         {
                   width=r.width;
                   height=r.height;
                   p=new int;//为新对象重新动态分配空间
                   *p=*(r.p);
         }
         ~Rect()//析构函数，释放动态分配空间
         {
             if(p!=NULL)
            {
             delete p;
            }
         }
private:
         int width;
         int height;
         int *p;

};

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