undefined reference to class::() C++

Question

I'm just learning constructor and destructor I'm following the tutorial this guy is doing bucky tutorial. I think the video is outdated? since I followed every single step he says and i'm still getting an error.

main.cpp

#include <iostream>
#include "TESTING.h"

using namespace std;

int main(){

    TESTING so;
    cout << "TEST" << endl;

}

TESTING.h

#ifndef TESTING_H
#define TESTING_H


class TESTING
{
    public:
        TESTING();
    protected:
        private:
};

#endif // TESTING_H

TESTING.cpp

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


TESTING::TESTING()
{
    cout << "TESTTTTT!!" << endl;
}

Error messages

\main.o:main.cpp undefined reference to 'TESTING::TESTING()'

Build log

mingw32-g++.exe   -c D:\C++\TESTING!\main.cpp -o D:\C++\TESTING!\main.o
mingw32-g++.exe  -o D:\C++\TESTING!\main.exe D:\C++\TESTING!\main.o   
D:\C++\TESTING!\main.o:main.cpp:(.text+0x52): undefined reference to `TESTING::TESTING()'
collect2.exe: error: ld returned 1 exit status
Process terminated with status 1 (0 minute(s), 1 second(s))
1 error(s), 0 warning(s) (0 minute(s), 1 second(s))

score 1 · Answer 1 · answered Aug 08 '15 at 06:15

1

You only build and link the main source file, not the TESTING source file. You need to compile TESTING.cpp as well, and then link with TESTING.o:

mingw32-g++.exe   -c D:\C++\TESTING!\TESTING.cpp -o D:\C++\TESTING!\TESTING.o
mingw32-g++.exe  -o D:\C++\TESTING!\main.exe D:\C++\TESTING!\main.o D:\C++\TESTING!\TESTING.o

answered Aug 08 '15 at 06:15

Some programmer dude

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How will i do that? I'm not used to this stuff yet. – Aug 08 '15 at 06:19
1

@JEEZSUSCRIZE Do like show in my answer? – Some programmer dude Aug 08 '15 at 06:23
I compiled the TESTING.cpp and i got an error undefined reference to WinMain@16 – Aug 08 '15 at 06:25
@JEEZSUSCRIZE Then it seems that MinGW tries to create a Windows GUI-type program. I don't know MinGW well enough, but it seems you need to add a flag to tell it to build a console program, you need to read the documentation. – Some programmer dude Aug 08 '15 at 06:27
ok thanks i just search it – Aug 08 '15 at 06:31

Peter · Answer 2 · 2015-08-08T06:51:33.653

1

You need to include both the compilation units in the build.

That means both source files need to be compiled, and both corresponding object files specified in the link command.

At present, only main.cpp is being compiled to an object, and only main.o is being linked.

edited Aug 08 '15 at 06:51

answered Aug 08 '15 at 06:18

Peter

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undefined reference to class::() C++

2 Answers2