CODEWITHSUNDEEP
c++classundefined
Kyle Genter
Kyle Genter

Reputation: 15

C++ undefined reference to class (1 header 2 cpp's)

I am reading a book (C++ for dummies) as well as watching youtube videos to learn how to code. I am currently struggling with very simple class functions.

Main.cpp

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>
#include "Test.h"
using namespace std;

int x;

int main(int nNumberofArgs, char* pszArgs[])
{
    combat fight;
    cout << x;
    fight.dodmg();
    cout << x;
    return 0;
}

Test.h my header file with the class

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>

using namespace std;

#ifndef TEST_H_INCLUDED
#define TEST_H_INCLUDED
class combat
{
public:
    int dodmg();
    void zero_out();
private:
    int x;
};


#endif // TEST_H_INCLUDED

Test.cpp class functions

#include "Test.h"


int combat::dodmg()
{

    x = x - 5;
    return x;
}

void combat::zero_out()
{
    x = 20
}

I tried to make this very simplistic just to figure out how to work a class. I included a lot of #includes just to try and make sure it wasn't something stupid like I needed strings.

I am not sure why but the videos I watched simply had the header say ifndef TEST_H (of their respective code, mine has an _INCLUDE as well, I tried deleting it and it still didn't work.

My unfortunate errors

on line 14 of main.cpp fight.dodmg(); it says

\Beginning_Programming-CPP\Playing_with_class\main.cpp|14|undefined reference to `combat::dodmg()'|

then below that 

||error: ld returned 1 exit status|

Upvotes: 0

Views: 2738

Answers (2)

alexpanter
alexpanter

Reputation: 1578

It sounds like you provide the wrong arguments for the compiler. Your header file (Test.h) simply provides signatures for the methods, but the implementations are given in the source file (Test.cpp).

This is an important part of writing C++ (or C) code. Your compiler does not automatically search for source files, so you need to tell it where to look, e.g.:

g++ -std=c++11 main.cpp Test.cpp -o main

Upvotes: 0

Jake Leveroni
Jake Leveroni

Reputation: 102

How are you compiling this? I think this is an issue because you arent compiling your Test.cpp file. If you arent already, try compiling with the command:

g++ main.cpp Test.cpp -o MyProgram

UPDATE:

Few things, you dont have a closing statement to your #ifndef directive in Text.h, you will need a constructor to set the value of x so i added one to the combat class also you were missing a semicolon in the zero_out function. I added comments to all the lines I changed.

Okay try this:

Test.h

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>

using namespace std;

#ifndef TEST_H_INCLUDED
#define TEST_H_INCLUDED
class combat
{
public:
   combat(); // added constructor
   int dodmg();
   void zero_out();
private:
   int x;
};

#endif // closed #ifndef

Text.cpp

#include "Test.h"

combat::combat() // implemented constructor
{
   x = 20;
}

int combat::dodmg()
{

   x = x - 5;
   return x;
}

void combat::zero_out()
{
   x = 20; // added ';'
}

Hope this helps,

Final edit: I dont think you really need your header guards in this scenario, you could remove the "#ifndef, #define, and the #endif" lines and not see a difference really

Upvotes: 2

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