Multiple Definition in non-inline members

[Nobody/Anonymous]

I am pretty sure there is a (very) simple explanation for the error that I am seeing but I cannot seem to figure out what it is. So, without much further ado:

1.) Code:

//main.cpp

include <cstdlib>

include <iostream>

include "mytest.cpp"

using namespace std;

int main(int argc, char *argv[])
{
system("PAUSE");
return EXIT_SUCCESS;
}

//mytest.cpp

ifndef ach_MYTEST_CPP_

define ach_MYTEST_CPP_

class mytest
{
public:
mytest();
~mytest();
private:
void Testing();
};

void mytest::Testing()
{
//any code here;
}

endif //ach_MYTEST_CPP_

2.) Compile log:

ompiler: Default compiler
Building Makefile: "D:\DevCpp\MyProjects\TestProjects\Makefile.win"
Executing make...
make.exe -f "D:\DevCpp\MyProjects\TestProjects\Makefile.win" all
g++.exe -c mytest.cpp -o mytest.o -I"D:/DevCpp/lib/gcc/mingw32/3.4.2/include" -I"D:/DevCpp/include/c++/3.4.2/backward" -I"D:/DevCpp/include/c++/3.4.2/mingw32" -I"D:/DevCpp/include/c++/3.4.2" -I"D:/DevCpp/include"

g++.exe main.o mytest.o -o "TestProjects.exe" -L"D:/DevCpp/lib"

mytest.o(.text+0x0):mytest.cpp: multiple definition of `mytest::Testing()'
main.o(.text+0x100):main.cpp: first defined here
collect2: ld returned 1 exit status

make.exe: *** [TestProjects.exe] Error 1

Execution terminated

3.) Clearly I have not correctly defined/declared "Testing" - but this is exactly the way many tutorials/books do it. Defining Testing inline solves the problem however.

I would appreciate any help

Regards,

ACH

[Nobody/Anonymous]

Thank You. That was crystal clear.

ACH

[Anonymous]

You have both #included mytest.cpp and separately compiled and linked it.

include is a simple textual replacement so by including mytest.cpp in main.cpp you have essentially defined class mytest in main.cpp (and it is compiled into main.o). You have additionally separately compiled mytest.cpp and linked it, so mytest.o has a definition of calss mytest and so does main.o.

You should have two separate files mytest.h and mytest.cpp, and include mytest.h in both main.cpp and mytest.cpp:

---

//mytest.h

ifndef ach_MYTEST_H_

define ach_MYTEST_H_

class mytest
{
public:
mytest();
~mytest();
private:
void Testing();
};

endif //ach_MYTEST_H_

---

---

//mytest.cpp

include "mytest.h"

void mytest::Testing()
{
//any code here;
}

// don't forget the constructor destructor as well!

Basically you never #include a .cpp file, and .h files should contain only declarations (as opposed to definitions) or in-line code.

Clifford