【发布时间】：2018-12-08 22:11:01
【问题描述】：
编译后我会收到这些消息
[error] 变量或字段 'Enqueue' 声明为 void 49 14 C:\weblinky1.cpp [错误] 变量或字段“入队”声明为无效
49 20 C:\weblinky1.cpp [Error] no match for 'operator*'（操作数类型是 'documents' 和 'node'）
49 35 C:\weblinky1.cpp [错误] 'operator*' 不匹配（操作数类型为'documents' 和'node'）
49 45 C:\weblinky1.cpp [错误] 'struct' 之前的预期主表达式
50 14 C:\weblinky1.cpp [Error] 变量或字段“dequeue”声明为无效
50 20 C:\weblinky1.cpp [Error] no match for 'operator*'（操作数类型是 'documents' 和 'node'）
51 14 C:\weblinky1.cpp [Error] 变量或字段 'getRear' 声明为 void
51 20 C:\weblinky1.cpp [Error] no match for 'operator*'（操作数类型是 'documents' 和 'node*'）
52 15 C:/weblinky1.cpp [Error] 变量或字段 'getFront' 声明为 void
52 21 C:\weblinky1.cpp [Error] no match for 'operator*'（操作数类型是 'documents' 和 'node*'）
C:\Users\marshalee\Desktop\DSLabTest1_1300054246\weblinky1.cpp 在函数'int main()'中：
60 11 C:\weblinky1.cpp [Error] no match for 'operator*'（操作数类型是 'documents' 和 'node*'）
114 49 C:\weblinky1.cpp [错误] 'enqueue' 未在此范围内声明
122 39 C:\weblinky1.cpp [错误] 'dequeue' 未在此范围内声明
126 27 C:\weblinky1.cpp [错误] 'operator==' 不匹配（操作数类型为 'documents' 和 'long long int'）
138 42 C:\weblinky1.cpp [错误] 'deletedocsize' 未在此范围内声明
147 48 C:\weblinky1.cpp [错误] 'searchfoldername' 未在此范围内声明
157 32 C:\weblinky1.cpp [错误] 'searchID' 未在此范围内声明
165 33 C:\weblinky1.cpp [错误] 'averagedocsize' 未在此范围内声明
173 29 C:\weblinky1.cpp [错误] 无法将 'isEmpty()' 从 'void' 转换为 'bool'
182 36 C:\weblinky1.cpp [错误] 'getRear' 未在此范围内声明
193 45 C:\weblinky1.cpp [错误] 'getFront' 未在此范围内声明
C:\weblinky1.cpp 在全局范围内：
221 19 C:\weblinky1.cpp [错误] 变量或字段“入队”声明为无效
下面是我的完整代码
enter code here/**
* Queue implementation using linked list in C.
*/
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#define CAPACITY 100 // Queue max capacity
/* Queue structure definition */
struct documents
{
int id;
char docname[50];
char foldername[50];
float docsize;
struct document * next;
struct document * previous;
};
//Delacre document variable
struct documents Queue;
//Create node for linked list
struct node
{
struct documents Queue;
struct node* previous;
struct node* next;
};
// Creating an empty linked list
struct node * rear = NULL;
struct node * front = NULL;
/* Queue size */
unsigned int size = 0;
void enqueue(Queue ** rear, Queue ** front, struct documents Queue);
void dequeue(Queue ** front);
void getRear(Queue * rear);
void getFront(Queue * front);
void isEmpty();
void isFull();
int main()
{
int ch, data;
Queue *rear, *front;
struct documents Queue;
int id;
float docsize;
char* docname;
char* foldername;
rear = NULL;
front = NULL;
/* Run indefinitely until user manually terminates */
while (1)
{
/* Queue menu */
printf("--------------------------------------------\n");
printf(" QUEUE LINKED LIST IMPLEMENTATION PROGRAM \n");
printf("--------------------------------------------\n");
printf("1. Enqueue\n");
printf("2. Dequeue\n");
printf("3. Delete by Size of Document\n");
printf("4. Display Documents based on Folder Name\n");
printf("5. Enter ID to Display Index where Documents was
found\n");
printf("6. Display Document Size Average\n");
printf("7. Size of the Queue\n");
printf("8. Get Rear\n");
printf("9. Get Front\n");
printf("0. Exit\n");
printf("--------------------------------------------\n");
printf("Select an option: ");
scanf("%d", &ch);
/* Menu control switch */
switch (ch)
{
case 1:
printf("\nEnter Document ID#: ");
scanf("%d", &Queue.id);
Queue.id = id;
printf("Enter Document size#: ");
scanf("%f", &Queue.docsize);
Queue.docsize = docsize;
printf("Enter Document name: ");
scanf("%s", &Queue.docname);
strcpy(Queue.docname, docname);
printf("Enter folder name: ");
scanf("%s", foldername);
strcpy(Queue.foldername, foldername);
// Enqueue function returns 1 on success
// otherwise 0
if (enqueue(&rear, &front, Queue))
printf("Document added to queue.");
else
printf("Queue is full.");
break;
case 2:
Queue = dequeue(&front);
// on success dequeue returns element removed
if (Queue == NULL)
printf("Queue is empty.");
else
printf("Queue => %d", Queue.front);
break;
//Delete by Size of Document
case 3:
printf("Enter Document size: ");
scanf("%f", &docsize);
deletedocsize(docsize);
break;
//Display Documents based on Folder Name
case 4:
printf("Enter Document Folder Name: ");
scanf("%s", foldername);
searchfoldername(foldername);
break;
//Enter ID to Display Index where Documents was found
case 5:
printf("Enter Document ID#: ");
scanf("%f", &id);
searchID(id);
break;
//Display Document Size Average
case 6:
averagedocsize();
break;
case 7:
// isEmpty() function returns 1 if queue is emtpy
// otherwise returns 0
if (isEmpty())
printf("Queue is empty.");
else
printf("Queue size => %d", size);
break;
//get rear of document queue
case 8:
data = getRear(rear);
if (Queue == Queue.rear)
printf("Queue is empty.");
else
printf("Rear => %d", Queue.rear);
break;
case 9:
Queue = getFront(front);
if (Queue == NULL)
printf("Queue is empty.");
else
printf("Front => %d", Queue.front);
break;
case 0:
printf("Exiting from application.\n");
exit(0);
default:
printf("Invalid choice, please input number between (0-
5).");
break;
}
printf("\n\n");
}
}
/**
* Enqueues/Insert an element at the rear of a queue.
* Function returns 1 on success otherwise returns 0.
*/
void enqueue(Queue *q)
{
Queue * temp= NULL;
// Check queue out of capacity error
if (isFull())
{
return 0;
}
// Create a new node of queue type
temp = (Queue *) malloc (sizeof(Queue));
// Assign data to new node
temp->docs= en;
// Initially new node does not point anything
temp->next = NULL;
temp->previous = NULL;
// Link new node with existing last node
if ( (*rear) )
{
(*rear)->next = temp;
}
// Make sure newly created node is at rear
*rear = temp;
// Link first node to front if its NULL
if ( !( *front) )
{
*front = *rear;
}
// Increment quque size
size++;
return 1;
}
/**
* Gets, element at rear of the queue. It returns the element
* at rear of the queue on success otherwise return as
* error code.
*/
int getRear(Queue * rear)
{
// if queue is empty otherwise rear.
return (isEmpty())
? NULL
: rear->Queue.rear;
}
/**
* Gets, element at front of the queue. It returns the element
* at front of the queue on success otherwise return as
* error code.
*/
int getFront(Queue * front)
{
// if queue is empty otherwise front.
return (isEmpty())
? NULL
: front->Queue.front;
}
/**
* Checks, if queue is empty or not.
*/
int isEmpty()
{
return (size <= 0);
}
/**
* Checks, if queue is within the maximum queue capacity.
*/
int isFull()
{
return (size > CAPACITY);
}
// deleting any node based on position
void Delete(int n)
{
struct documents temp1 =front;
if(n == 1){
front= temp1->next;
free(temp1);
return;
}
int i for(i =0; i<n-2; i++)
temp1 = temp1->next;
struct node* temp2 = temp1->next;
temp1->next = temp2 -> next;
free(temp2);
}
//or using this method
void Dequeue(int n)
{
struct documents temp1;
if(Front == NULL)
{
printf("Queue is empty.\n");
}
else
{
int currentIndex = 0;
struct documents *temp1 = (struct documents*)malloc(sizeof(struct
documents));
bool traversing = true;
tem1 = Front;
temp1 = temp1->Queue;
while(temp1 !=NULL) {
if(temp1.id == n)
{
temp1->previous->next=temp1->next;
free(temp1);
printf("Item Deleted", currentIndex);
return;
}
currentIndex++;
temp1 = temp1->next;
if (temp1 == NULL) {
temp1 = temp1->previous;
}
temp1 = temp1->Queue;
}
}
}
//search by foldername
void searchfoldername(char foldername[])
{
struct documents Queue;
if(Front == NULL)
{
printf("Queue is empty.\n");
}
else
{
struct documents *tempp = (struct documents*)malloc(sizeof(struct
documents));
bool traversing = true;
int currIndex = 0;
tempp = Front;
tempy = tempp->Queue;
Front = Front->next;
while(traversing) {
if(strcmp(tempy->foldername, foldername) == 0))
{
printf(" ID: %d\n", tempy->id);
printf("Document Name: %s\n", tempy->docname);
printf("Folder Name: %s\n", tempy->foldername);
printf("Document Size: %d\n", tempy->docsize);
printf("Document positioned at index: %d", currIndex);
return tempy.foldername;
}
currIndex++;
tempp = tempp->next;
if (tempp == NULL) {
tempp = tempp->previous;
}
tempy = tempp->Queue;
}
}
}
//delete document size
Void deletedocsize(int docsize)
{
struct documents Queue;
if(Front == NULL)
{
printf("Queue is empty.\n");
}
else
{
struct documents *tempp = (struct documents*)malloc(sizeof(struct
documents));
bool traversE = true;
int currIndex = 0;
tempp = Front;
tempy = tempp->Queue;
front = front->next;
while(traversE) {
if(strcmp(tempy->docsize, docsize) <= Queue.docsize))
{
free(tempp);
return;
}
currIndex++;
tempp = tempp->next;
if (tempp == NULL) {
tempp = tempp->previous;
}
tempy = tempp->Queue;
}
}
}
};
//Enter ID to Display Index where Documents was found
void searchID(int id)
{
struct documents Queue;
if(Front == NULL)
{
printf("Queue is empty.\n");
}
else
{
struct documents *tempp = (struct documents*)malloc(sizeof(struct
documents));
bool traversing = true;
int currIndex = 0;
tempp = Front;
tempy = tempp->Queue;
Front = Front->next;
while(traversing) {
if(strcmp(tempy->id, id) == Queue.id))
{
printf("Document positioned at index: %d", currIndex);
return tempy.id;
}
currIndex++;
tempp = tempp->next;
if (tempp == NULL) {
tempp = tempp->previous;
}
tempy = tempp->Queue;
}
}
}
//find and display the Average of all document size
void averagedocsize()
{
struct documents Queue;
if (front == NULL)
{
printf("\n ooops List is Empty\n");
}
else
{
struct documents *tempp = (struct documents*)malloc(sizeof(struct
documents));
int count = 0;
tempp = front;
Queue = tempp->Queue;
while (tempp != NULL)
{
if(strcmp(Queue.docsize, docsize) == 0) {
sum=0;
while (count<=rearindex)
{
sum = sum + docsize;
average =rearindex;
}
count++;
}
tempp = tempp->next;
if (tempp == NULL) {
printf("Average Document Size is : %d\n\n", average);
break;
}
Queue = tempp->;
}
free(tempp);
}
}
【问题讨论】：
-
Queue被not 声明为类型，因此Queue **[或Queue *] 无效。而且，您的typedef声明了struct名称Book但不是Book的类型（即它是合法的，但格式有点错误）。试试：typedef struct Book { what_you_already_have } Book;然后，做void Enqueue(Book **rear, Book **front, Book *en)。当您执行struct Book Queue;时，Queue仅仅是struct Book类型的全局实例——它确实不 声明了Queue的type。 -
当我编译这段代码时，我得到了一堆错误，但没有一个是你说的错误。请阅读并关注instructions for producing a minimal, complete, verifiable example program。
-
请不要大喊大叫。
-
虽然代码肯定不正确，但很难看出它将如何产生
[error] variable or field 'Enqueue' declared void- 似乎这不是产生错误的代码。仔细复制并粘贴您的代码和错误 - 不要删除内容 - 例如错误消息将包含行号等信息 - 不要删除它，并确保您发布的代码包含该行。此外，您的标题与正文无关 - 标题更广泛（太宽泛），而正文非常具体（关于错误消息）。 -
从风格上看，
Queue这个名字太笼统了，不能专门指书的队列，而且类型不是队列，而是队列的一个元素。typedef Book* BookQueue ;可能更有意义，那么Enqueue参数将具有BookQueue*类型。
标签： c linked-list