我编写了一个LinkedList类和一个测试函数来测试我的类。但是，我在编译和运行程序时遇到了一些问题。有三个文件：test.cpp LinkedList.cpp和LinkedList.h。
TEST.CPP：
#include "LinkedList.cpp"
#include <string>
#include <iostream>
using namespace std;
// Loading Array into Linked List for testing
template <class T, size_t n>
void fillArrayIn(LinkedList<T> &list, T (&arr)[n])
{
unsigned int length = sizeof(arr) / sizeof(*arr);
for (unsigned int i = 0; i < length; i++)
{
list.append(arr[i]);
}
}
int main()
{
// Integer LinkedList
cout << "=====================================" << endl;
cout << "Test for Integer LinkedList" << endl
<< endl;
LinkedList<int> intList;
cout << "Is List Empty? " << (intList.isEmpty() ? "Yes" : "No") << endl
<< endl; // Test isEmpty()
int intArray[] = {1, 2, 5, 6, 9, 0, 1};
fillArrayIn(intList, intArray); // Test appending
cout << "Array Loaded" << endl;
cout << "Is List Empty? " << (intList.isEmpty() ? "Yes" : "No") << endl;
intList.printAll();
intList.insert(*(new int(100)), 3); // Test insertion
cout << endl
<< "Insert 100 to position 3" << endl;
intList.printAll();
cout << "Insert integer outside the List: "
<< (intList.insert(*(new int(100)), 100) ? "Success" : "Fail") << endl
<< endl; // Test illegal insertion
cout << "Find the position of integre 9: " << intList.positionOf(9) << endl; // Test get the position of element in List
cout << "Find the position of not existed element: " << intList.positionOf(20) << endl
<< endl; // Test get the position of not existed element
cout << "The element at position 0 is " << *(intList.get(0)) << endl; // Test get element
cout << "The element at position 7 is " << *(intList.get(7)) << endl;
cout << "The element at position 8 is " << intList.get(8) << endl
<< endl;
cout << "Deleting 100 from list: "
<< (intList.remove(*(new int(100))) ? "Sucess" : "Fail") << endl;
intList.printAll();
cout << "Deleting not existed element from list: "
<< (intList.remove(*(new int(20))) ? "Sucess" : "Fail") << endl;
intList.printAll();
}
LinkedList.cpp：
#include <string>
#include <iostream>
#include "LinkedList.h"
using namespace std;
template <class T>
LinkedList<T>::LinkedList()
{
head = new Node(NULL);
}
template <class T>
void LinkedList<T>::append(T &_data)
{
Node *current = head;
while (current->next)
{
current = current->next;
}
current->next = new Node(&_data);
// cout << _data <<" has been appended to the list."<<endl;
}
template <class T>
bool LinkedList<T>::insert(T &_data, const int position)
{
Node *current = head;
Node *previous = head;
for (int i = position + 1; i > 0; i--)
{
if (!current->next)
return false;
previous = current;
current = current->next;
}
previous->next = new Node(&_data);
previous->next->next = current;
return true;
}
template <class T>
T *LinkedList<T>::get(int position)
{
Node *current = head;
for (int i = position + 1; i > 0; i--)
{
if (!current->next)
return NULL;
current = current->next;
}
return current->data;
}
template <class T>
bool LinkedList<T>::isEmpty()
{
if (head->next)
return false;
return true;
}
template <class T>
bool LinkedList<T>::remove(const T &_data)
{
Node *current = head;
Node *previous = current;
while (current->next)
{
previous = current;
current = current->next;
if (*(current->data) == _data)
{
previous->next = current->next;
return true;
}
}
return false;
}
template <class T>
int LinkedList<T>::positionOf(const T &_data)
{
Node *current = head;
unsigned int position = -1;
while (current->next)
{
current = current->next;
position++;
if (*(current->data) == _data)
return position;
}
return -1;
}
template <class T>
void LinkedList<T>::printAll()
{
Node *current = head;
while (current->next)
{
current = current->next;
cout << *(current->data) << " ";
}
cout << endl;
}
template <class T>
class LinkedList<T>::Node
{
public:
Node(T *_data) : data(_data) {}
T *data;
Node *next;
};
LinkedList.h：
#ifndef LINKEDLIST_H
#define LINKEDLIST_H
template <class T>
class LinkedList
{
public:
LinkedList();
void append(T &);
bool insert(T &, const int);
T *get(int);
bool isEmpty();
bool remove(const T &);
int positionOf(const T &);
void printAll();
private:
class Node;
Node *head;
};
#endif
当我用g++编译我的程序时，它成功编译并给出了预期的结果：
=====================================
Test for Integer LinkedList
Is List Empty? Yes
Array Loaded
Is List Empty? No
1 2 5 6 9 0 1
Insert 100 to position 3
1 2 5 100 6 9 0 1
Insert integer outside the List: Fail
Find the position of integre 9: 5
Find the position of not existed element: -1
The element at position 0 is 1
The element at position 7 is 1
The element at position 8 is 0
Deleting 100 from list: Sucess
1 2 5 6 9 0 1
Deleting not existed element from list: Fail
1 2 5 6 9 0 1
当我尝试使用cl（VS2017）编译我的程序时，编译也是成功的。但是，当我运行程序时，它会卡在某一点上。运行结果：
=====================================
Test for Integer LinkedList
Is List Empty? No
后来，我尝试在Visual Studio中创建一个项目。令人惊讶的是，这一次，它运行没有任何问题。如何才能正确使用cl进行编译？谢谢你，如果你能给我一些提示！我是C ++的新学习者。
B.T.W. cl生成的目标文件和可执行文件超过200KB，远远超过g++生成的大约14KB。
我建议您对代码进行以下更改。我不知道这是否会改变行为，但值得一试。
head的构造函数中将nullptr初始化为List。
template <class T>
LinkedList<T>::LinkedList() : head(nullptr)
{
// Creating a Node with NULL does not make sense to me.
// head = new Node(NULL);
}
next的构造函数中将nullptr初始化为Node。让它未初始化肯定会导致问题。
Node(T *_data) : data(_data), next(nullptr) {}
您对空列表的检查使用Node属性next。
/* ... */
if (head->next)
/* ... */
使用带有Node指针参数的构造函数后，next未显式初始化。
Node(T *_data) : data(_data) {}
这些线都与第一个输出差异相关
列表是空的吗？没有 列表是空的吗？是
我倾向于偏执于初始化，并将使用修改后的构造函数和显式初始化：
Node(T *_data) : data(_data), next(NULL) {}