Multiply defined symbols error

[trno224]

I am writing a program and I need to put certain things in different .cpp and .h files but when I try to seperate certain things into .cpp files I get an error that says "error LNK2005: "struct node_2 * beginning" (?beginning@@3PAUnode_2@@A) already defined in Autocomplete.obj" and I think based on the error it has to do with "*beginning" in my Autocomplete.h file but I am not positive and I do not know how to fix it. Any help would be greatly appreciated! Here are my files..

Term.h

#ifndef TERM_H
#define TERM_H
#include <iostream>
using namespace std;
struct node
{
	string text;
	int number;
	struct node *next;
};
class Term
{
public:
	struct node* SortedMerge(node* a, node* b);
	void FrontBackSplit(node* source, node** front, node** back);
	void MergeSort(struct node** head);
	void print(node *node, int num);
	void push(node** head, string data, int num);
};
#endif 

Autocomplete.h

#ifndef AUTOCOMPLETE_H
#define AUTOCOMPLETE_H
#include "Term.h"
struct node_2
{
	string txt;
	int digits;
	struct node_2 *after;
	struct node_2 *before;
}*beginning;
class Autocomplete
{
public:
	void CreateList(string file);
	void Insert(int num,string file);
	void print(int results);
	int sort_weight();
	void search(string txt, string prefix, int num);
	void Delete(string file);
};
#endif 

Term.cpp

#include "Term.h"
#include <string>
void Term :: push(node** head, string data, int num)
{
    node *temp = new node;
    temp->text = data;
	temp -> number = num;
    temp->next = (*head);
    (*head)    = temp;
}
void Term :: MergeSort(struct node** head)
{
	node* temp_head = *head;
	node* a;
    node* b;
    if ((temp_head == NULL) || (temp_head->next == NULL))
    {
		return;
    }
	FrontBackSplit(temp_head, &a, &b);
    MergeSort(&a);
    MergeSort(&b);
    *head = SortedMerge(a, b);
}
node* Term :: SortedMerge(struct node* a, struct node* b)
{
    node* result = NULL;
    if (a == NULL)
        return b;
    else if (b==NULL)
        return a;
    if (a->text <= b->text)
	{
        result = a;
        result->next = SortedMerge(a->next, b);
    }
    else
    {
        result = b;
        result->next = SortedMerge(a, b->next);
    }
    return result;
}
void Term :: FrontBackSplit(node* source, node** front, node** back)
{
    node* fast;
    node* slow;
    if (source==NULL || source->next==NULL)
    {
        *front = source;
        *back = NULL;
    }
    else
    {
        slow = source;
        fast = source->next;
        while (fast != NULL)
        {
            fast = fast->next;
            if (fast != NULL)
            {
                slow = slow->next;
                fast = fast->next;
            }
        }
        *front = source;
        *back = slow->next;
        slow->next = NULL;
    }
}
void Term :: print(node *node, int num)
{
	int count = 0;
    while (node != NULL)
    {
		count++;
        cout<<count << " " << node->number << " " << node-> text << endl;
        node = node->next;
	}
}

Autocomplete.cpp
code]
#include "Autocomplete.h"
#include <string>
void Autocomplete :: CreateList(string file)
{
node_2 *temp;
temp = new(node_2);
temp -> txt = file;
temp -> after = NULL;
if (beginning == NULL)
{
temp -> before = NULL;
beginning = temp;
}
else
{
while (beginning -> after != NULL)
{
beginning = beginning -> after;
beginning -> after = temp;
temp -> before = beginning;
}
}
}
void Autocomplete :: Insert(int num, string file)
{
node_2 *temp, *temp_2;
temp_2 = beginning;
temp = new(node_2);
temp -> txt = file;
temp -> digits = num;
if (temp_2 -> after == NULL)
{
temp_2 -> after = temp;
temp -> after = NULL;
temp -> before = temp_2;
}
else
{
temp -> after = temp_2 -> after;
temp -> after -> before = temp;
temp_2 -> after = temp;
temp -> before = temp_2;
}
}
int Autocomplete:: sort_weight ()
{
node_2 * temphead = beginning;
int temproll;
string tempname;
int counter = 0;
while (temphead )
{
temphead = temphead->after;
counter++;
}
temphead = beginning -> after;

if (counter == 1)
{
return 1;
}
for (int j=0; j<counter; j++)
{
while (temphead->after)
{
if (temphead->digits < temphead->after->digits)
{
temproll = temphead->digits;
temphead->digits = temphead->after->digits;
temphead->after->digits = temproll;
tempname = temphead->txt;
temphead->txt = temphead->after->txt;
temphead->after->txt = tempname;
temphead = temphead->after;
}
else
temphead = temphead->after;
}
temphead = beginning;
}
}
void Autocomplete :: search(string txt, string prefix, int num)
{
Autocomplete sort;
for(int i = 1; i <= prefix.size(); i++)
{
if((prefix.substr(i - 1, 1) == txt.substr(i,1)))
{
continue;
}
else
{
return;
}
}
sort.Insert(num,txt);
}
void Autocomplete :: print(int results)
{
int line_number = 1;
node_2 *temp_2;
temp_2 = beginning;
if( temp_2->txt == "")
{
//proceed to followinf line skipping over this plan line
temp_2 = temp_2-> after;
}

//enter loop if temp_2 != null (have not reached end of file)
while (temp_2 != NULL && temp_2-> txt != "")
{
if(results <= 0)
{
return;
}
//output line number and each line in the list till you reach the end
cout << temp_2 -> digits << " " << temp_2 -> txt << endl;
//progress to next line
temp_2 = temp_2 -> after;
//increment line number
line_number += 1;
results--;
}
}
void Autocomplete :: Delete(string file)
{
////declare nodes temp and set equal to start which is declared in the class LinkedList. So it starts from beginning.
struct node_2* temp = beginning;
while(temp -> after != NULL)
{
beginning = beginning -> after;
delete temp;
temp = beginning;
}
}
[/code]

main.cpp

#include <fstream>
#include <string>
#include <ctime>
#include <chrono>
#include "Term.h"
#include "Autocomplete.h"
int main()
{
	node* a = NULL;
	Term txt_file;
	string file;
	int num;
	string file_name;
	ifstream infile;
	int size = 0;
	int largest_pos = 0;
	string prefix;
	int results = 0;
	Autocomplete sort;
	int position = 0;
	sort.CreateList(file);
	//ask user for file to open and store in variable
	cout << "What file would you like to open: ";
	getline(cin, file_name);
	infile.open(file_name);
	//check if file name is valid
	if(infile.fail())
	{
		//if not display error message and end program
		cout <<"The file cannot be opened, terminating program!" << endl;
		system("pause");
		exit(0);
	}
	const auto cpu_start = std::clock() ;
	//use loop to read through file
	while(infile >> num && (getline(infile, file)))
	{
		txt_file.push(&a, file, num);
		//call function to insert each line in file into linked list one following the other
	}
	txt_file.MergeSort(&a);
	const auto cpu_end = std::clock() ;
	const auto cpu_milliseconds = (((cpu_end-cpu_start) * 1000.0 / CLOCKS_PER_SEC) * .001) ;

	// compute elapsed real time
	using namespace std::chrono ;

	std::cout << endl << "Time for sorting list is " << cpu_milliseconds << " seconds.\n" << endl << endl;
	txt_file.print(a, num);
	while(true)
	{
		
		infile.clear();
		infile.seekg(infile.beg);
		cout <<"Please enter query: ";
		getline(cin, prefix);
		if(prefix == "Exit" || prefix == "exit")
		{
			cout <<"You have ended the program!" << endl;
			cout <<"Thanks for using it and have a nice day!" << endl;
			system("Pause");
			return 0;
		}
		cout <<"How many results would you like to return" << endl;
		cin >> results;
		const auto cpu_start = std::clock() ;
		while(infile >> num && (getline(infile, file)))
		{
			sort.search(file, prefix, num);
		}
	
		if(sort.sort_weight() == 1)
		{
			cin.clear();
			cin.ignore();
			cout << "There are no matches to your search query." << endl;
			continue;
		}
		sort.print(results);
		const auto cpu_end = std::clock() ;
		const auto cpu_milliseconds = (((cpu_end-cpu_start) * 1000.0 / CLOCKS_PER_SEC) * .001) ;

		// compute elapsed real time
		using namespace std::chrono ;

		std::cout << endl << endl << endl << "Time for searching and sorting all matched terms is " << cpu_milliseconds << " seconds.\n" << endl << endl;

		sort.Delete(file);
		cin.clear();
		cin.ignore();
	}

	//txt_file.print(file_name);
	system("pause");
	return 0;
}

[ne555]

> I think based on the error it has to do with "*beginning" in my
> Autocomplete.h file
yes http://www.cplusplus.com/forum/general/140198/
In Autocomplete.h

struct node_2{
	//...
}; //no need to do everything in one line
extern node_2 *beginning; //declaration 

In Autocomplete.cpp
node_2 *beginning; //definition


Also, consider if you really need to have a global variable.

[trno224]

Ok got it! Thanks so much for the help and information! I spent so much time trying to figure out this problem!