为定义模板，用类型参数 (type parameter) T来标识任意类型，用类型变量T替换Pair类中所有的int。最后， 在类定义前加上一行template<typename T>即得到一个模板。
以下程序为List类模板定义与实现
// list.cpp : 定义控制台应用程序的入口点。 // #include "stdafx.h" #include <string> #include <iostream> #include <cassert> using namespace std; template<typename T> class List; template<typename T> class Iterator; /** A class to hold the nodes of the linked list. */ template<typename T> class Node { public: /** Constructs a node for a given data value. @param s the data to store in this node */ Node(T s); private: T data; Node<T>* previous; Node<T>* next; friend class List<T>; friend class Iterator<T>; }; /** An iterator denotes a position in the list or past the end of the list */ template<typename T> class Iterator { public: /** Constructs an iterator that is not attached to any list */ Iterator(); /** Looks up the value at a position. @return the value of the Node to which the iterator points */ T operator*() const; /** Adances the iterator to the next position */ void operator++(int dummy); /** Moves the iterator to the previous position. */ void operator--(int dummy); /** Compares two iterators. @param b the iterator to compare with this iterator @return true if this iterator and b are equal */ bool operator==(Iterator<T> b) const; /** Compares two iterators. @param b the iterator to compare with this iterator @return true if this iterator and b are equal */ bool operator!=(Iterator<T> b) const; private: Node<T>* position; Node<T>* last; friend class List<T>; }; /** A linked list of values of a given type. @param T the type of the list values */ template<typename T> class List { public: /** Constructs an empty list */ List(); /** Constructs a list as a copy of another list. @param b the list to copy */ List(const List<T>& b); /** Deletes all nodes of this list. */ ~List(); /** Assigns another list to this list. @param b the list to assign @return a reference to this list */ List<T>& operator=(const List<T>& b); /** Appends an element to the list @param s the value to append */ void push_back(T s); /** Inserts an element into the list. @param iter the position before which to inssert @param s the value to append */ void insert(Iterator<T> iter, T s); /** Removes an element from the list. @param i the position to remove @param an iterator pointing to the element after the element after the erased element */ Iterator<T> erase(Iterator<T> i); /** Gets the beginning position of the list. @return an iterator pointing to the beginning of the list */ Iterator<T> begin(); /** Gets the past-the-end position of the list @return an iterator pointing past the end of the list */ Iterator<T> end(); private: /** Copies another list to this list. @param b the list to copy */ void copy(const List<T>& b); /** Deletes all nodes of this list. */ void free(); Node<T>* first; Node<T>* last; }; template<typename T> List<T>::List() { first = NULL; last = NULL; } template<typename T> List<T>::~List() { free(); } template<typename T> List<T>::List(const List<T>& b) { first = NULL; last = NULL; copy(b); } template<typename T> List<T>& List<T>::operator=(const List<T>& b) { if (this != &b) { free(); copy(b); } return *this; } template<typename T> void List<T>::push_back(T s) { Node<T>* newnode = new Node<T>(s); if (last == NULL) /* list is empty */ { first = newnode; last = newnode; } else { newnode->previous = last; last->next = newnode; last = newnode; } } template<typename T> void List<T>::insert(Iterator<T> iter, T s) { if (iter.position == NULL) { push_back(s); return; } Node<T>* after = iter.position; Node<T>* before = after->previous; Node<T>* newnode = new Node<T>(s); newnode->previous = before; newnode->next = after; after->previous = newnode; if (before == NULL) /* insert at beginning*/ first = newnode; else before->next = newnode; } template<typename T> Iterator<T> List<T>::erase(Iterator<T> i) { Iterator<T> iter = i; assert(iter.position != NULL); Node<T>* remove = iter.position; Node<T>* before = remove->previous; Node<T>* after = remove->next; if (remove == first) first = after; else before->next = after; if (remove == last) last = before; else after->previous = before; iter.position = after; delete remove; return iter; } template<typename T> Iterator<T> List<T>::begin() { Iterator<T> iter; iter.position = first; iter.last = last; return iter; } template<typename T> Iterator<T> List<T>::end() { Iterator<T> iter; iter.position = NULL; iter.last = last; return iter; } template<typename T> Iterator<T>::Iterator() { position = NULL; last = NULL; } template<typename T> T Iterator<T>::operator*() const { assert(position != NULL); return position->data; } template<typename T> void Iterator<T>::operator++(int dummy) { assert(position != NULL); position = position->next; } template<typename T> void Iterator<T>::operator--(int dummy) { if (position == NULL) position = last; else position = position->previous; assert(position != NULL); } template<typename T> bool Iterator<T>::operator!=(Iterator<T> b) const { return position != b.position; } template<typename T> Node<T>::Node(T s) { data = s; previous = NULL; next = NULL; } template<typename T> void List<T>::copy(const List<T>& b) { for (Iterator<T> p = b.begin(); p != b.end(); p++) push_back(*p); } template<typename T> void List<T>::free() { while (begin() != end()) erase(begin()); } int _tmain(int argc, _TCHAR* argv[]) { List<string> staff; staff.push_back("Cracker, Carl"); staff.push_back("Hacker, Harry"); staff.push_back("Lam, Larry"); staff.push_back("Sandman, Susan"); /* add a value in fourth place */ Iterator<string> pos; pos = staff.begin(); pos++; pos++; pos++; staff.insert(pos, "Reindeer, Rudolf"); /* remove the value in second place */ pos = staff.begin(); pos++; staff.erase(pos); /* print all values */ for (pos = staff.begin(); pos != staff.end(); pos++) cout << *pos << " "; system("pause"); return 0; }
