Templated BST "Already Initialized" Error

Hi all,

I'm implementing a linked BST to create a simple program to store, search, and retrieve records. Whenever I instantiate a new CityRecord object in my main function as follows:

Code:

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SearchTree<int, CityRecord> stree;
SearchTree<int, CityRecord>::Position p;

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I get error

Code:

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Error        3        c:\users\pogos\desktop\classes fall 2011\csci 220\projects\project 4\project 4\project 4\searchtree.h
        91        error C2437: 'LBTree' : already initialized

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which refers to

Code:

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SearchTree() : LBTree() {}

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in the search tree header file. I don't get this error when I comment out the main function body.

There are several files and hundreds of lines of code that would be ridiculous to post here, so could anyone please point me in the right direction in terms of where to properly start declaring a new search tree in my main function? I can give more info on the code as needed. Thank you! :)

C2437 is shown here: Compiler Error C2437
It means that you are initialising LBTree (the base class) twice. The code you've posted does not demonstrate that so I'm 99.9% sure that your real code has other stuff in it which is the real cause of the problem. Afterall, if your constructor were really exactly as you posted then it is the same as the default constructor, in which case you should delete it and this would logically have to cause the same fault, which is impossible.
Post the entire unedited constructor for SearchTree.

Quote:

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Originally Posted by iMalc

C2437 is shown here: Compiler Error C2437
It means that you are initialising LBTree (the base class) twice. The code you've posted does not demonstrate that so I'm 99.9% sure that your real code has other stuff in it which is the real cause of the problem. Afterall, if your constructor were really exactly as you posted then it is the same as the default constructor, in which case you should delete it and this would logically have to cause the same fault, which is impossible.
Post the entire unedited constructor for SearchTree.

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That is actually the whole constructor for SearchTree.

LBTree is actually a typedef of a templated LBT class as follows:

Code:

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typedef LinkedBinaryTree<LBTEntry> LBTree;

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with

Code:

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template <typename Key, typename Element,

typename LBTEntry = Entry<Key, Element> >

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on top of SearchTree.h.

LinkedBinaryTree's constructor is as follows:

Code:

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LinkedBinaryTree() : _root(new Node), nodes(1) { }

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I also find it strange that the compiler wasn't reporting the error when the main function was commented out. I think I need to modify

Code:

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SearchTree <int, CityRecord> stree;

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to include the Entry class. I tried

Code:

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SearchTree <Entry <int, CityRecord> > stree;

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but I get a too few arguments error, which makes sense, but I dont understand what additional argument I have to add since I only need the key and the CityRecord object.

The errors after the above modification are:

Code:

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error C2976: 'SearchTree' : too few template arguments
error C2133: 'stree' : unknown size
error C2512: 'SearchTree' : no appropriate default constructor available

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Note: The SearchTree constructor I provided above is instructor supplied

Quote:

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Originally Posted by misterpogos

That is actually the whole constructor for SearchTree.
Note: The SearchTree constructor I provided above is instructor supplied

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Okay, then try deleting it. It does nothing anyway. What happens then?

Quote:

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Originally Posted by misterpogos

I also find it strange that the compiler wasn't reporting the error when the main function was commented out. I think I need to modify

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Visual Studio doesn't complain about template code that can never compile if it doesn't actually need it to compile to produce the working program. Without a main it mustn't need to compile the templated code.

Whenever working with template code, remember this advice.
Always explicitly instantiate the class. This allows the compiler to properly check for errors.
You do this by

template class_name<template_args>;

Thank you guys! I truly appreciate it! I resorted to writing untemplated code (templates weren't required, but they were encouraged). Unfortunately I wasn't able to grasp the concept fully in time.