我明天正在为我的考试练习一些编码，因为某些原因我无法让我的程序运行。我一直收到错误：
Undefined reference ..pract\ArrayListType\main.cpp:47: error: undefined reference to 'arrayListType<std::string>::Print() const'
这是我到目前为止的代码，从我看到它看起来非常好。 尝试评论代码行无济于事。 不知道什么是错的。
//头文件：
#ifndef ARRAYLISTTYPE_H
#define ARRAYLISTTYPE_H
using namespace std;
template <class elemType>
class arrayListType
{
public:
const arrayListType<elemType>& operator= (const arrayListType<elemType>&);
//Overloads the assignment operator
bool isEmpty() const;
//Determines if list is empty
bool isFull() const;
//Determines if the list is full
int listSize() const;
//Function to determine number of elements in the list
int maxListsize() const;
//Function to determine the size of the list
void Print() const;
//Function to output the elements in the list
bool isItemAtEqual(int location, const elemType& item) const;
//Function to determine if an item entered is the same as another item at a specific location
void insertAt(int location, elemType& insertItem);
//Function to insert an item at a specified location
void insertEnd(const elemType& insertItem);
//Function to insert an item at the end of the list
void removeAt(int location);
//Function to remove an item at a specified location
void retrieveAt(int location, const elemType& retItem) const;
//Function to retrieve the item located at the position specified
void replaceAt(int location, const elemType& repItem);
//Function to replace a value in the list at a specified location
void clearList();
//Function to remove all the elements from the list
int seqSearch(const elemType& item) const;
//Function to search the list for a given item
void insert(const elemType& insertItem);
//function to insert an item into the list
void remove(const elemType& removeItem);
//function to remove an item from the list
arrayListType(int size = 100);
//Constructor to initialize the size of the list to 100
arrayListType(const arrayListType<elemType>& otherList);
//Copy constructor
~arrayListType();
//Destructor
protected:
elemType *list;
int length;
int maxSize;
};
#endif // ARRAYLISTTYPE_H
//定义文件
#include <iostream>
#include <string>
#include "arraylisttype.h"
using namespace std;
template <class elemType>
bool arrayListType<elemType>::isEmpty() const {
return (length == 0);
}
template <class elemType>
bool arrayListType<elemType>::isFull() const {
return (length == maxSize);
}
template <class elemType>
int arrayListType<elemType>::listSize() const {
return length;
}
template <class elemType>
int arrayListType<elemType>::maxListsize() const {
return maxSize;
}
//All the above functions have a running time of O(1) - constant as they will
//produce the same result int eh same time due to only having one line to run.
//_____________________________________________________________________________
template <class elemType> // O(n)
void arrayListType<elemType>::Print() const {
for (int i = 0; i <length; i++) {
cout << list[i] << " ";
}
cout << endl;
}
//The print function will have a running time of O(n) as it is linear to the size of the list
//and how full the list is.
template <class elemType> // O(1) - constant
bool arrayListType<elemType>::isItemAtEqual(int location, const elemType &item) const {
return(list[location] == item);
}
template <class elemType> //O(n)
void arrayListType<elemType>::insertAt(int location, elemType &insertItem) {
if (location < 0 || location >= maxSize)
cerr << "The position to be inserted at is out of range!";
else
if (length >= maxSize)
cerr << "Cannot insert in a full list";
else {
for (int i = length; i > location; i--)
list[i] = list[i - 1]; // Move elements down.
list[location] = insertItem; // insert the item at the specified location
length++;
}
}
template <class elemType>
void arrayListType<elemType>::insertEnd(const elemType &insertItem) {
if (length >= maxSize)
cerr << "Cannot insert in a full list";
else {
list[length] = insertItem;
length++;
}
}
template <class elemType>
void arrayListType<elemType>::removeAt(int location) {
if (location < 0 || location >= maxSize)
cerr << "the location fo the item to be retrieved is out of bounds";
else {
for (int i = location; i < length - 1; i++)
list[i] = list[i+1];
length--;
}
}
template <class elemType>
void arrayListType<elemType>::retrieveAt(int location, const elemType& retItem) const {
if (location < 0 || location >= maxSize)
cerr << "the location fo the item to be retrieved is out of bounds";
else (retItem = list[location]);
}
template <class elemType>
void arrayListType<elemType>::replaceAt(int location, const elemType &repItem) {
if (location < 0 || location >= length)
cerr << "The location of the item to be replaced is out of bounds.";
else
list[location] = repItem;
}
template <class elemType>
void arrayListType<elemType>::clearList() {
length = 0;
}
template <class elemType>
arrayListType<elemType>::arrayListType(int size) {
if (size < 0) {
cerr << "The array size must be positive. creating an array of size 100";
maxSize = 100;
}
else
maxSize = size;
length = 0;
list = new elemType[maxSize];
assert(list!=NULL);
}
template <class elemType>
arrayListType<elemType>::~arrayListType() {
delete [] list;
}
template <class elemType>
arrayListType<elemType>::arrayListType(const arrayListType<elemType> &otherList) {
maxSize = otherList.maxSize;
length = otherList.length;
list = new elemType[maxSize];
for (int j = 0; j < length; j++)
list[j] = otherList.list[j];
}
template <class elemType>
const arrayListType<elemType>& arrayListType<elemType>::operator=(const arrayListType<elemType>& otherList) {
if (this != &otherList) {
delete [] list;
maxSize = otherList.maxSize;
length = otherList.length;
list = new elemType[maxSize];
assert(list != NULL);
for (int i = 0; i < length; i++)
list[i] = otherList.list[i];
}
return *this;
}
template <class elemType>
int arrayListType<elemType>::seqSearch(const elemType &item) const {
int loc;
bool found = false;
for (loc = 0; loc < length; loc++)
if (list[loc] == item) {
found = true;
break;
}
if (found)
return loc;
else
return -1;
}
template <class elemType>
void arrayListType<elemType>::insert(const elemType &insertItem) {
int loc;
if (length == 0)
list[length++] == insertItem;
else if (length == maxSize)
cerr << "Cannot insert into full list.";
else {
loc == seqSearch(insertItem);
if (loc == -1)
list[length++] = insertItem;
else
cerr << "The item to be inserted is already in the list."
<< "\nNo duplicates are allowed.";
}
}
template <class elemType>
void arrayListType<elemType>::remove(const elemType &removeItem) {
int loc;
if (length == 0)
cerr << "Cannot delete from an empty list";
else {
loc = seqSearch(removeItem);
if (loc != -1)
removeItem(loc);
else
cout << "The item to be deleted is not int eh list.";
}
}
//主
#include <iostream>
#include <string>
#include "arraylisttype.h"
using namespace std;
int main()
{
arrayListType<int> intList(100);
arrayListType<string> stringList;
int number;
cout << "List 10: Enter 5 integers: ";
for (int counter = 0; counter < 5; counter++) {
cin >> number;
intList.insertAt(counter, number);
}
cout << endl;
cout << "List 19: The list you entered is: ";
intList.Print();
cout << endl;
cout << "Line 20: Enter the item to be deleted: ";
cin >> number;
intList.remove(number);
cout << "Line 23: After removing " << number << ", the lsit is: " << endl;
intList.Print();
cout << endl;
string str;
cout << "Line 27: Enter 5 strings: ";
for (int counter = 0; counter < 6; counter++) {
cin >> str;
stringList.insertAt(counter, str);
}
cout << endl;
cout << "Line 34: The list you entered is: ";
stringList.Print();
cout << endl;
cout << "Line 37: Enter the string to be deleted: ";
cin >> str;
stringList.remove(str);
cout << "Line 40: After removing " << str << " the list is: " << endl;
stringList.Print();
return 0;
}
答案 0 :(得分：0)
使用模板类或方法时，编译器会生成代码，编译器需要访问定义。因此，您必须将模板方法定义放在头文件本身，并包含您使用它们的位置。模板是编译时功能而非运行时。模板定义不能与cpp文件隔离。