VC，C2027错误！
用VC6.0调试《C++编程思想》上的一个例子，报错error C2027: use of undefined type 'Stack<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >'，请问什么原因，改怎么改？
谢谢！
//: C16:TStack2.h
#ifndef TSTACK2_H
#define TSTACK2_H
template<class T> class Stack {
struct Link {
T* data;
Link* next;
Link(T* dat, Link* nxt)
: data(dat), next(nxt) {}
}* head;
public:
Stack() : head(0) {}
~Stack();
void push(T* dat) {
head = new Link(dat, head);
}
T* peek() const {
return head ? head->data : 0;
}
T* pop();
// Nested iterator class:
class iterator; // Declaration required
friend class iterator; // Make it a friend
class iterator { // Now define it
Stack::Link* p;
public:
iterator(const Stack<T>& tl) : p(tl.head) {}
// Copy-constructor:
iterator(const iterator& tl) : p(tl.p) {}
// The end sentinel iterator:
iterator() : p(0) {}
// operator++ returns boolean indicating end:
bool operator++() {
if(p->next)
p = p->next;
else p = 0; // Indicates end of list
return bool(p);
}
bool operator++(int) { return operator++(); }
T* current() const {
if(!p) return 0;
return p->data;
}
// Pointer dereference operator:
T* operator->() const {
require(p != 0,
"PStack::iterator::operator->returns 0");
return current();
}
T* operator*() const { return current(); }
// bool conversion for conditional test:
operator bool() const { return bool(p); }
// Comparison to test for end:
bool operator==(const iterator&) const {
return p == 0;
}
bool operator!=(const iterator&) const {
return p != 0;
}
};
iterator begin() const {
return iterator(*this);
}
iterator end() const { return iterator(); }
};
template<class T> Stack<T>::~Stack() {
while(head)
delete pop();
}
template<class T> T* Stack<T>::pop() {
if(head == 0) return 0;
T* result = head->data;
Link* oldHead = head;
head = head->next;
delete oldHead;
return result;
}
#endif // TSTACK2_H ///:~
#include "stdafx.h"
//: C16:TStack2Test.cpp
#include "TStack2.h"
#include "require.h"
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
ifstream file("TStack2Test.cpp");
assure(file, "TStack2Test.cpp");
Stack<string> textlines;
// Read file and store lines in the Stack:
string line;
while(getline(file, line))
textlines.push(new string(line));
int i = 0;
// Use iterator to print lines from the list:
Stack<string>::iterator it = textlines.begin();
Stack<string>::iterator* it2 = 0;
while(it != textlines.end()) {
cout << it->c_str() << endl;
it++;
if(++i == 10) // Remember 10th line
it2 = new Stack<string>::iterator(it);
}
cout << (*it2)->c_str() << endl;
delete it2;
return 1;
} ///:~
[解决办法]
VC6对标准支持不好。升级编译器
[解决办法]
#include <string> // 该头文件必须放置在“TStack2.h”之前
#include "TStack2.h"
#include "require.h"
#include <iostream>
#include <fstream>
