Question

在此队列中使用链接列表实现，因此显示功能显示正确的结果，但SizeOf（）也由相同的逻辑实现，如果调用未显示正确的答案。为什么会这样？

// A C program to demonstrate linked list based implementation of queue
#include <stdlib.h>
#include <stdio.h>
#include<bits/stdc++.h>
using namespace std;

// A linked list (LL) node to store a queue entry
struct QNode
{
    int key;
    struct QNode *next;
};

// The queue, front stores the front node of LL and rear stores the last node of LL
struct Queue
{
    struct QNode *front, *rear;
};

// A utility function to create a new linked list node.
struct QNode* newNode(int k)
{
    struct QNode *temp = (struct QNode*)malloc(sizeof(struct QNode));
    temp->key = k;
    temp->next = NULL;
    return temp;
}

// A utility function to create an empty queue
struct Queue *createQueue()
{
    struct Queue *q = (struct Queue*)malloc(sizeof(struct Queue));
    q->front = q->rear = NULL;
    return q;
}

// The function to add a key k to q
void enQueue(struct Queue *q, int k)
{
    // Create a new LL node
    struct QNode *temp = newNode(k);

    // If queue is empty, then new node is front and rear both
    if (q->rear == NULL)
    {
    q->front = q->rear = temp;
    return;
    }

    // Add the new node at the end of queue and change rear
    q->rear->next = temp;
    q->rear = temp;
}

// Function to remove a key from given queue q
struct QNode *deQueue(struct Queue *q)
{
    // If queue is empty, return NULL.
    if (q->front == NULL)
    return NULL;

    // Store previous front and move front one node ahead
    struct QNode *temp = q->front;
    q->front = q->front->next;

    // If front becomes NULL, then change rear also as NULL
    if (q->front == NULL)
    q->rear = NULL;
    return temp;
}

void Display(struct Queue *q)
{
    if(q==NULL)
    {
        cout<<"No elements"<<endl;
        return;
    }
    else{
        while(q->front->next!=NULL)
        {
            cout<<q->front->key<<" ";
            q->front=q->front->next;
        }
        cout<<q->front->key<<" ";
    }
}

int SizeOf(struct Queue *q)
{
    int count=0;
    if(q==NULL)
    {
        cout<<"No elements"<<endl;
        return 0;
    }
    else{
        while(q->front->next!=NULL)
        {
            count++;
            q->front=q->front->next;
        }
      count++;
    }
    return count;
}
// Driver Program to test anove functions
int main()
{
    struct Queue *q = createQueue();

    enQueue(q, 10);
    enQueue(q, 20);
    deQueue(q);
    deQueue(q);
    enQueue(q, 30);
    enQueue(q, 40);
    enQueue(q, 50);
    enQueue(q, 40);
    enQueue(q, 50);


    struct QNode *n = deQueue(q);
    if (n != NULL)
    printf("Dequeued item is %d\n", n->key);



    cout<<"The Queue is Displayed as follows:"<<endl;
    Display(q);

    cout<<"The Queue Size is as follows:"<<endl;
    int no=SizeOf(q);
    cout<<no<<endl;`enter code here`
    return 0;
}

Display（）的输出是40 50 40 50但是SizeOf（）的输出是1.有什么问题？

在指针显示函数

0 个答案: