Undefined reference - Help

[Stefano Mtangoo]

Hi All,
I'm having trouble with my code.
When I compile I get Undefined reference to class::method where by class and method are my class and method. I get my methods from akrip32.dll

I,m at work so I have no source files, but I will attach them later when I lay hold on them.
Thanks all :)

EDIT: I use MINGW that comes with Codeblocks 8.02

[Ancient Dragon]

The project is probably not linking with the library that is produced for that dll, most likely akrip32.lib, or libakrip32.a, or something like that.

[Stefano Mtangoo]

Thanks sir, Here are the files for the project plus the akrip which is found on http://akrip.sourceforge.net/download.html

[Stefano Mtangoo]

Errors I get are as below and I have attached the Source code and DLL (the DLL is LGPLed)
C:\Program Files\CodeBlocks\Projects\testingAkrip\main.cpp||In member function `DWORD CDRip::GetVersion()':|
C:\Program Files\CodeBlocks\Projects\testingAkrip\main.cpp|38|warning: control reaches end of non-void function|
C:\Program Files\CodeBlocks\Projects\testingAkrip\main.cpp||In function `int GetCDLists()':|
C:\Program Files\CodeBlocks\Projects\testingAkrip\main.cpp|70|warning: control reaches end of non-void function|
C:\Program Files\CodeBlocks\Projects\testingAkrip\main.cpp|57|warning: 'lpcd' might be used uninitialized in this function|
obj\Release\app.o:app.cpp:(.text+0x2c)||undefined reference to `CDRip::GetCDLists(CDLIST*)'|
||=== Build finished: 1 errors, 3 warnings ===|

[Ancient Dragon]

In function GetCDLists() (main.cpp) you have an object also named GetCDLists. Rename that object to something else, such as GList, or whatever. Just don't give it the same name as the function name.

Then a little later in that function you attempt to call the function with a parameter. That function does not take any parameters.

CDRip::GetVersion: you have to put a return value at the end of that function.

[Stefano Mtangoo]

Thanks alot.
I'm working on your comments :)

[Stefano Mtangoo]

Here is the updated code.
When I run the app, it just loads the DLL then crashes :(
I don't understand what I do wrong. BTW I'm just starting with Windows DLL and I want to implement simple ripping function of the Akrip32.dll

[Ancient Dragon]

Probably because you are passing uninitialized variables to functions. If your compiler didn't produce these warnings then use a different compiler.

1>c:\dvlp\test9\test9\main.cpp(59) : warning C4700: uninitialized local variable 'lpcd' used
1>c:\dvlp\test9\test9\app.cpp(16) : warning C4700: uninitialized local variable 'lister' used

[Stefano Mtangoo]

it didnt!
I use GCC compiler that comes with Code::Blocks. may be I should change compiler to windows

[Ancient Dragon]

windows is not a compiler -- its an operating system. IMHO vc++ 2008 Express is one of the best compilers/IDEs available today. It produces a lot of errors and warnings that other compilers completly miss. And its debugging facilities can't be beat by any other IDE/compiler on any operating system.

Instead of changing compilers at this point, find out how to increase the warning level so that it will produce better errors and warnings.

[kvprajapati]

LPCDLIST is pointer to struct.
GetCDLists code :

if (GCDLists !=0){
        LPCDLIST lpcd;  // Pointer to struct
        GCDLists(lpcd); //  <-- no place for data
  .....

if (GCDLists !=0){
            CDLIST lp;         // struct variable
            GCDLists(&lp);  //  an address of struct 
            std::cout <<   lp.cd[0].info.vendor;
 .....

[Stefano Mtangoo]

LPCDLIST is pointer to struct.
GetCDLists code :

if (GCDLists !=0){
        LPCDLIST lpcd;  // Pointer to struct
        GCDLists(lpcd); //  <-- no place for data
  .....

if (GCDLists !=0){
            CDLIST lp;         // struct variable
            GCDLists(&lp);  //  an address of struct 
            std::cout <<   lp.cd[0].info.vendor;
 .....

That completely solved the Problem.
Thanks you two guys :) You have saved me alot of pains

[Stefano Mtangoo]

Ok, your code works, but I have not understood the changes you made. Can you explain a little bit of changes and what I was doing wrong. Also why Did you changed LPCDLIST lpcd; to GCDLists(&lp); ?? also what about std::cout << lp.cd[0].info.vendor; ??

Thanks

[kvprajapati]

app.cpp

# include "main.h"
#include <iostream>
//testing function below

//main application
int main()
{
    CDRip instance;
    //DWORD ver = instance.GetVersion();
    //Get Version
    //std::cout<<"The Version is: "<<ver<<std::endl;
    //Get CDList
    CDLIST lister;   // object of CDLIST struct

    instance.GetCDLists(&lister);  // Pass an address of lister 
    return 0;
}

main.cpp

....
int CDRip::GetCDLists(LPCDLIST lpcd){
    //define a pointer to the function
    typedef int (*ptrGetCDLists)(LPCDLIST lpcd);
    //Create a pointer function to access the DLL function
    ptrGetCDLists GCDLists;

    //Load the DLL
    HINSTANCE hDLL = LoadLibrary("akrip32.dll");
    //DLL loaded successful?
    if (hDLL!=0){
        std::cout<<"Loaded DLL"<<std::endl;
        //Get Function address
        GCDLists = (ptrGetCDLists)GetProcAddress(hDLL, "GetCDList");
        // Function loaded Succesful?
        if (GCDLists !=0){
            GCDLists(lpcd);
            std::cout <<   lpcd->cd[0].info.vendor;
            FreeLibrary(hDLL);
        }
        // Function Loading failed?
        else{
            std::cout<<"Error, can't load function GetVersion!"<<std::endl;
            FreeLibrary(hDLL);
        }
    }
    //DLL Loading failed
    else std::cout<<"Error! Cannot Load Library"<<std::endl;
    return 0;
}
...

[Stefano Mtangoo]

Thank you :)