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我必須用C++編寫一個隊列,使用我之前創建的List文件,而且我要花費大量時間來編譯。連接兩個C++文件(List.cc和Queue.cc)時出現的問題
我目前遇到的問題是,我編譯時出現錯誤: Queue.h:7:2:錯誤:「名單」沒有指定類型
如何去正確連接我的隊列文件和我的列表文件?
下面是我使用的文件: List.h
//an item in the list
struct ListNode {
int _value;
ListNode * _next;
};
class List {
public:
//Head of list
ListNode * _head;
int remove_front();
void insertSorted(int val);
void append (int val);
void prepend (int val);
int lookup(int _value);
int remove(int val);
void print();
List();
~List();
};
List.cc
//
// Implement the List class
//
#include <stdio.h>
#include "List.h"
ListNode * _head = new ListNode();
//remove the first node in the list
int
List::remove_front(){
int ret;
if(_head == 0){
return -1;
}
ret = _head->_value;
ListNode *temp = new ListNode();
temp = _head->_next;
delete(_head);
_head = temp;
return ret;
}
//
// Inserts a new element with value "val" in
// ascending order.
//
void
List::insertSorted(int val){
ListNode* new_node = new ListNode();
new_node->_value = val;
ListNode* current = new ListNode();
if(_head == 0){
_head = new_node;
}else{
current = _head;
ListNode* prev = 0;
while(current != 0){
if(new_node->_value > current->_value){
prev = current;
current = current->_next;
}else{
break;
}
}
if(current == _head){
new_node->_next = _head;
_head = new_node;
}else{
new_node->_next = current;
prev->_next = new_node;
}
}
}
//
// Inserts a new element with value "val" at
// the end of the list.
//
void
List::append(int val){
//create a new node to hold the given value
ListNode *new_node = new ListNode();
new_node->_value = val;
//if the list is empty
if(_head == 0){
//set the new node to be the head
_head = new_node;
return ;
}
//create a node pointer to the current position (starting at the head)
ListNode *current = new ListNode();
current = _head;
//Loop through the list until we find the end
while(current->_next != NULL){
current = current->_next;
}
current->_next = new_node;
}
//
// Inserts a new element with value "val" at
// the beginning of the list.
//
void
List::prepend(int val){
ListNode *new_node = new ListNode;
new_node->_value = val;
if(_head == 0){
_head = new_node;
return ;
}
ListNode *temp = new ListNode;
temp = _head;
_head = new_node;
_head->_next = temp;
}
// Removes an element with value "val" from List
// Returns 0 if succeeds or -1 if it fails
int
List:: remove(int val){
if(_head == 0){
printf("List is already empty.\n");
return -1;
}
ListNode *current = new ListNode();
ListNode* prev = new ListNode();
current = _head;
while(current != 0){
if(current->_value == val){
if(current == _head){
_head = _head->_next;
delete(current);
return 0;
}else{
prev->_next = current->_next;
delete(current);
return 0;
}
}else{
prev = current;
current = current->_next;
}
}
return -1;
}
// Prints The elements in the list.
void
List::print(){
ListNode* current = new ListNode();
while(current != 0){
printf("%d\n", current->_value);
current = current->_next;
}
}
//
// Returns 0 if "value" is in the list or -1 otherwise.
//
int
List::lookup(int val){
ListNode * current = new ListNode();
current = _head;
while(current != NULL){
if(current->_value == val){
return 0;
}
else{
current = current->_next;
}
}
return -1;
}
//
// List constructor
//
List::List(){
}
//
// List destructor: delete all list elements, if any.
//
List::~List(){
ListNode* current = _head;
while(current != NULL){
ListNode* next = current->_next;
delete current;
current = next;
}
}
Queue.h
#ifndef LIST_H
#define LIST_H
class Queue {
public:
List* queue_list;
void enqueue(int val);
int dequeue();
Queue();
~Queue();
};
#endif
Queue.cc
#include <stdio.h>
#include "List.h"
#include "Queue.h"
List *queue_list = new List();
void
Queue::enqueue(int val){
this->queue_list->prepend(val);
}
int
Queue::dequeue(){
int value = this->queue_list->remove_front();
return value;
}
Queue::Queue(){
//do nothing
}
Queue::~Queue(){
}
queue_main.cc
#include <stdio.h>
#include "Queue.h"
#include "List.h"
Queue *queue;
int main(){
}
感謝您的幫助!
這不是一個準確的規則。如果編譯器需要知道相關類型的大小,你只需要包含'List.h'。如果它是一個成員變量。如果您將它用作參數,假設沒有隱式轉換,則僅使用前向聲明即可保證安全。 –
這很有道理。感謝您的幫助! – user3253680
@MarkIngram你是對的,規則調整。 ;-) – stefan