C++中指针的引用及其应用实例-yiteyi-C++库

喜欢推荐人对于简单的数据类型，我们可以参考指针 .

null

                     // CPP program to demonstrate references to pointers.                   
                     #include <iostream>                   
                     using                               namespace                               std;                   
                             
                     int                               main()                   
                     {                   
                                         int                               x = 10;                   
                             
                                         // ptr1 holds address of x                   
                                         int                               * ptr1 = &x;                   
                             
                                         // Now ptr2 also holds address of x.                   
                                         // But note that pt2 is an alias of ptr1.                   
                                         // So if we change any of these two to                   
                                         // hold some other address, the other                   
                                         // pointer will also change.                   
                                         int                               *& ptr2 = ptr1;                   
                             
                                         int                               y = 20;                   
                                         ptr2 = &y;                   
                             
                                         // Below line prints 20, 20, 10, 20                   
                                         // Note that ptr1 also starts pointing                   
                                         // to y.                   
                                         cout << *ptr1 <<                               " "                               << *ptr2 <<                               " "                   
                                         << x <<                               " "                               << y;                   
                             
                                         return                               0;                   
                     }                   

输出：

20 20 10 20

上面的应用是什么？ 考虑一个情况，我们传递一个函数的指针，我们希望函数修改指针指向其他东西，并且我们希望这些更改在调用方中反映。例如，编写一个链表函数来改变它的头，我们将引用传递给指向头的指针，以便该函数可以改变头（另一种方法是返回头）。我们也可以通过使用双指针 .

                     // A C++ program to demonstrate application                   
                     // of reference to a pointer.                   
                     #include <iostream>                   
                     using                               namespace                               std;                   
                             
                     // A linked list node                   
                     struct                               Node {                   
                                         int                               data;                   
                                         struct                               Node* next;                   
                     };                   
                             
                     /* Given a reference to pointer to the head of                   
                                         a list, insert a new value x at head */                   
                     void                               push(                               struct                               Node *&head,                               int                               x)                   
                     {                   
                                         struct                               Node* new_node =                               new                               Node;                   
                                         new_node->data = x;                   
                                         new_node->next = head;                   
                                         head = new_node;                   
                     }                   
                             
                     // This function prints contents of linked                   
                     // list starting from head                   
                     void                               printList(                               struct                               Node* node)                   
                     {                   
                                         while                               (node != NULL) {                   
                                         cout << node->data <<                               " "                               ;                   
                                         node = node->next;                   
                                         }                   
                     }                   
                             
                     /* Driver program to test above functions*/                   
                     int                               main()                   
                     {                   
                                         /* Start with the empty list */                   
                                         struct                               Node* head = NULL;                   
                                         push(head, 1);                   
                                         push(head, 2);                   
                                         push(head, 3);                   
                             
                                         printList(head);                   
                             
                                         return                               0;                   
                     }                   

输出：

3 2 1

文章版权归作者所有，未经允许请勿转载。

THE END

技术文章