Why do I keep getting Redefinition of Class Error? C++

Question

I keep getting the error: "Redefinition of 'CBSTree'" and "Previous definition is here" on all my functions in my cbstree.cpp code. I'm not sure why. I believe I have the correct include guards and such. Help would be very much appreciated! Thank you.

main.cpp

#include    <iostream>
#include    <cstdlib>
using namespace std;
#include    "cbstree.h"

// define to show duplicate insertions
#define SHOW_INSERT

// defined constants
const   int         BUFLEN = 256;

cbstree.cpp

#include    <fstream>
#include    <iostream>
#include    <cstdlib>
using namespace std;
#include    "cbstree.h"

template    <typename  NodeType>
CBSTree<NodeType>::CBSTree(const CBSTree<NodeType>  &other)
{
    m_root = NULL;
    if(m_root != other.m_root)
    {
        DestroyTree();
        m_root = CopyTree(other.m_root);
    }
}  // end of "CBSTree<NodeType>::CBSTree"

cbstree.h

#ifndef CBIN_SEARCH_TREE_HEADER
#define CBIN_SEARCH_TREE_HEADER

#include    "ctreenode.h"

// class declaration
template    <typename  NodeType>
class   CBSTree
{
public:
    // constructors and destructor
    CBSTree() : m_root(NULL) {}
    CBSTree(const CBSTree  &other);
    virtual ~CBSTree() { DestroyTree(); }
...

#include    "cbstree.cpp"
#endif  // CBIN_SEARCH_TREE_HEADER

ctreenode.h

#ifndef CTREE_NODE_HEADER
#define CTREE_NODE_HEADER

#include    <iostream>
using namespace std;

template    <typename NodeValueType>
class   CTreeNode
...

#endif  // CTREE_NODE_HEADER

You should _never_ include `.cpp` files. If you want to put template definitions in another file (which I wouldn't recommend) name them differently. When `cbstree.cpp` is compiled it will `#include "cbstree.h"` which then will `#include "cbstree.cpp"` and you have the definition twice in one translation unit. — Lukas-T, Dec 01 '20 at 07:40
Maybe this (admitteldy C, but same concept) answers your question already https://stackoverflow.com/q/46439321/7733418 If you agree I will delete my answer below and propose it as duplicate. Or maybe others propose better (C++ specific) duplicates. — Yunnosch, Dec 01 '20 at 08:05
I got an upvote by somebody else than question author. Please excuse me hence for not deleting my answer, even if this gets "duplicated". If it is considered valuable it should probably stay.... — Yunnosch, Dec 01 '20 at 13:53

score 1 · Answer 1 · answered Dec 01 '20 at 08:01

If you include the definition into more than one cpp file you get redefinitions.

And you do so with both lines #include "cbstree.h".
(This answer ignores that you indirectly include the cbstree.cpp into itself; though that might be a shortcoming of your inconsistent MRE.)

As churill mentioned, including cpp files will sooner or later get you into trouble.
Learn about the goals of headers and code files please. There are Q/As here on that.

Why do I keep getting Redefinition of Class Error? C++

1 Answers1