C / C++ / MFC

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#include < stack ><br />
#include < iostream ><br />
#include < string ><br />
<br />
using namespace std;<br />
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template < typename E > <br />
class history<br />
{<br />
	private:<br />
                //i'm using to stacks to record history<br />
		stack < E > back_list; <br />
		stack < E > forward_list;<br />
<br />
	public:<br />
		history();<br />
		void add_entry(const E & entry);<br />
		E & undo();<br />
		E & redo();<br />
		bool no_undo();<br />
		bool no_redo();<br />
};<br />
<br />
template < typename E ><br />
void history < E >::add_entry(const E & entry)<br />
{<br />
	back_list.push(entry);<br />
	while(!forward_list.empty())<br />
	{<br />
		forward_list.pop();<br />
		<br />
	}<br />
}<br />
<br />
template < typename E > <br />
E & history < E >::undo()<br />
{<br />
	E entry;<br />
	if(!back_list.empty())<br />
	{<br />
		entry = back_list.top();<br />
		back_list.pop();<br />
		forward_list.push(entry);<br />
		<br />
	}<br />
<br />
	return(entry);<br />
}<br />
<br />
template < typename E > <br />
E & history < E >::redo()<br />
{<br />
	E entry;<br />
	if(!forward_list.empty())<br />
	{<br />
		entry = forward_list.top();<br />
		forward_list.pop();<br />
		back_list.push(entry);<br />
	}<br />
	return(entry);<br />
}<br />
<br />
template < typename E > <br />
bool history < E >::no_undo()<br />
{<br />
	if(back_list.empty())<br />
		return(1);<br />
	else return (0);<br />
}<br />
<br />
template < typename E > <br />
bool history < E >::no_redo()<br />
{<br />
	if(forward_list.empty())<br />
		return (1);<br />
	else return (0);<br />
}<br />
<br />
<br />
<br />
void main()<br />
{<br />
	history <int> his;<br />
	his.add_entry(2);<br />
	int out;<br />
	out = his.undo();<br />
	cout<<out;<br />
	<br />
}<br />
<br />

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Linking...<br />
history.obj : error LNK2001: unresolved external symbol "public: __thiscall history<int>::history<int>(void)" (??0?$history@H@@QAE@XZ)<br />
Debug/history.exe : fatal error LNK1120: 1 unresolved externals<br />
Error executing link.exe.<br />
<br />
history.exe - 2 error(s), 0 warning(s)<br />