Problem in Template function. Uncomprehensive error message

[eypros]

Hello again,

I was testing a code from Accelerated C++ and (as usual) came up with some errors. The fact is I don't get what to correct in this peace of code. The code is

#include <iostream>
#include <string>
#include <iterator>
#include "split.h"

using namespace std;

int main()
{
    string s;
    while (getline(cin, s))
    split(s, ostream_iterator<string>(cout, "\n"));
    return 0;
}

with split.cpp being:

#include <string>
#include <algorithm>
#include "space.h"

using namespace std;

template <class Out> // changed
void split(const string& str, Out os) { // changed
typedef string::const_iterator iter;
iter i = str.begin();
while (i != str.end()) {
// ignore leading blanks
i = find_if(i, str.end(), not_space);
// find end of next word
iter j = find_if(i, str.end(), space);
// copy the characters in [i, j)
if (i != str.end())
*os++ = string(i, j); // changed
i = j;
}
}

and for space.cpp:

#include <cctype> //for isspace()

// true if the argument is whitespace, false otherwise
bool space(char c)
{
return isspace(c);
}

// false if the argument is whitespace, true otherwise
bool not_space(char c)
{
return !isspace(c);
}

The error message is

undefined reference to `void split<std::ostream_iterator<std::basic_string<char, std::char_traits<char>,
 std::allocator<char> >, char, std::char_traits<char> > (std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, 
std::ostream_iterator<std::basic_string<char, std::char_traits<char>, 
std::allocator<char> >, char, std::char_traits<char> >)'|

.

OK I don't know a lot about Template functions but I don't know what to search for in here. I figure out that ostream_iterator<string>(cout, "\n") is valid because I used it alone and compiled fine. So the problem should be in split but how do I spot it (and correct it)? I even tried a different string iterator as a second argument in the function split but also an error message occurred.

Any clue about this problem?

[WR417H]

are you saving split and space as .cpp files instead of .h files?

[eypros]

No I use also header files (I didn't mention) as well as space.cpp and split.cpp:

split.h:

#ifndef GUARD_split_2_h
#define GUARD_split_2_h

template <class Out> // changed
void split(const std::string& str, Out os);

#endif 

And space.h:

#ifndef GUARD_space_h
#define GUARD_space_h
bool space(char c);
bool not_space(char c);
#endif