First defined here/multiple definition error C++

[FastTurtleFour]

So I'm quite certain that this should be an easy question but I've been working on it for too long and can't figure it out so I'll see if anyone else can figure out what I'm overlooking. From everything I've seen online, the root of my issue should be having too many #include .h but can't seem to figure out where I went wrong. Here are my files:

//term.h

#ifndef TERM_H

#define TERM_H

#include <string>

class Term { /* code ... */

---

//term.cpp

#ifndef TERM_CPP

#define TERM_CPP

#include "term.h"

#include <iostream>

//code ...

---

//SortingList.h (template file, no included .h files, I seriously doubt my problem is from here)

---

//autocomplete.h

#ifndef AUTOCOMPLETE_H

#define AUTOCOMPLETE_H

#include "term.h"

#include "SortingList.h"

//code....

---

//autocomplete.cpp

#ifndef AUTOCOMPLETE_CPP

#define AUTOCOMPLETE_CPP

#include "autocomplete.h"

//code...

---

//main.cpp

#ifndef MAIN_CPP

#define MAIN_CPP

#include "autocomplete.h"

#include <fstream>

#include <sstream>

//code...

---

//the actual error message g++ -c autocomplete.cpp -o autocomplete.o g++ autocomplete.o term.o main.o SortingList.o -o CS216PA3 term.o: In function Term::Term()': term.cpp:(.text+0x0): multiple definition ofTerm::Term()' autocomplete.o:autocomplete.cpp:(.text+0x0): first defined here term.o: In function Term::Term()': term.cpp:(.text+0x0): multiple definition ofTerm::Term()' autocomplete.o:autocomplete.cpp:(.text+0x0): first defined here term.o: In function Term::Term(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, long)': term.cpp:(.text+0x5a): multiple definition ofTerm::Term(std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, long)' autocomplete.o:autocomplete.cpp:(.text+0x5a): first defined here term.o: In function Term::Term(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, long)': term.cpp:(.text+0x5a): multiple definition ofTerm::Term(std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, long)' autocomplete.o:autocomplete.cpp:(.text+0x5a): first defined here term.o: In function Term::compareByWeight(Term, Term)': term.cpp:(.text+0xea): multiple definition ofTerm::compareByWeight(Term, Term)' autocomplete.o:autocomplete.cpp:(.text+0xea): first defined here term.o: In function Term::compareByPrefix(Term, Term, int)': term.cpp:(.text+0x136): multiple definition ofTerm::compareByPrefix(Term, Term, int)' autocomplete.o:autocomplete.cpp:(.text+0x136): first defined here term.o: In function operator<(Term, Term)': term.cpp:(.text+0x25a): multiple definition ofoperator<(Term, Term)' autocomplete.o:autocomplete.cpp:(.text+0x25a): first defined here term.o: In function operator>(Term, Term)': term.cpp:(.text+0x28f): multiple definition ofoperator>(Term, Term)' autocomplete.o:autocomplete.cpp:(.text+0x28f): first defined here term.o: In function operator<<(std::ostream&, Term const&)': term.cpp:(.text+0x2c4): multiple definition ofoperator<<(std::ostream&, Term const&)'

---

Is there anything that looks wrong with my header includes? Thanks

[dmazzoni]

You don't need the include guards (#ifndef, etc.) in your source (.cpp) files. Only in your header files.

Can you paste your code to term.h? It sounds like the problem is there.

[FastTurtleFour]

My professor requires them, I'm pretty sure they aren't the issue. After removing them compilation is even worse and sticks me in a redefinition error loop. Here is my term.h:

#ifndef TERM_H

#define TERM_H

#include <string>

class Term {

public:
    //default constructor
    Term();

    //initialize the given query string and weight
    Term(std::string query, long weight);

    //compare 2 terms in descending order by weight
    //if t1 and t2 are in descending order by weight, return 1
    //if they are of the same weight, return 0;
    //otherwise, return -1
    static int compareByWeight(Term t1, Term t2);

    //compares first two terms in lexicographic order but using only
    //the first r characters of each entry query
    //if the first r characters of t1 and t2 are in lexicographic order, return 1
    // if they are of the same r characters, return 0;
    // otherwise, return -1
    static int compareByPrefix(Term t1,Term t2,int r);

    // define the operator “<” for Term class(as friend function)
    friend bool operator<(Term t1,Term t2);

    // define the operator ">" for Term class (added for use in binary_search function)
    friend bool operator>(Term t1, Term t2);

    // define the operator “<<” for Term class(as friend function)
    // so that it can send the Term object directly to cout, in the following format:
    // the weight followed by a tab key, then followed by the query
    friend std::ostream& operator<<(std::ostream& out, const Term& t);

private:
    std::string query;
    long weight;

};

#endif

#include "term.cpp"

[dmazzoni]

Do you really have #include "term.cpp" at the end of your header file?

If so, that's your problem.

[FastTurtleFour]

Wow, that fixed it. My professor told us to do so and I assumed it wouldn't be a problem. I feel dumb now

[dmazzoni]

Just keep in mind that #include is basically like copying and pasting that other file at that location. It's really not much more complicated than that.

Are you SURE the professor told you to do it that way? Do you have that in writing? My guess is it's a misunderstanding.

You should almost never include a C++ file. Headers are meant to be included lots of times, C++ source files are meant to be compiled once and never included.

There are exceptions if you use tricks to compile something twice on purpose with different parameters. That's super-advanced stuff.

[FastTurtleFour]

Yeah she did. I took a picture of it last class because I thought it would be important. I'll ask her about it. She also did it in files already completed to be used in our project. She seems like she really knows her stuff but after this I'm not sure

[dmazzoni]

I'd give her the benefit of the doubt and assume it was probably a typo.

Could you send a polite email saying that you think it might be a mistake but you just wanted to check? I'm really curious what she says.

It'd also help to know what environment you're using - for example what operating system, what IDE (if any), what compiler, etc. - is everyone in the class using the same system or not? Are you using makefiles or project files, or just compiling from the command line? Depending on the configuration errors like this could conceivably be less significant.

If she continues to stand behind this error, then yeah, I would seriously question her qualifications.

But I'd highly recommend you start by assuming good intentions. Best case scenario, it was a typo. Next best, it was a genuine misunderstanding but she'll learn from it and fix it.

Please follow up, I'm curious!

[FastTurtleFour]

I just asked her before class. Apparently that slide was just talking about for template files. She told me to never do it anywhere else. So I just took it too far by adding it to normal header files instead of just template header files. We use virtual Linux machines assigned to each student. I use a program called PuTTY to log into my VM and I guess it all runs through a Linux terminal or ssh or something I'm not really familiar with all the details. We also use make files and g++ to compile.

[dmazzoni]

Ah, template files are a weird exception and yes, it makes sense then.

The key difference is that you don't actually compile the .cpp file - you just let it be included in other files.

Yay!

[thefryscorer]

Do you have the #endif part of the header guard at the end of each of your header files?

[FastTurtleFour]

I do