Link errors using FANN | 易学教程

问题

I'm trying to build a basic FANN (Fast Artificial Neural Network) project on Windows with MinGW. However, whenever I try to link the executable, I run into a bunch of undefined reference to errors. Interestingly, if I don't link the library at all, I get more errors, implying that at least some of the library is working. The code for the file I'm trying to compile and link is:

#include "doublefann.h"

int main() {
    const unsigned int num_input_neurons = 9;
    const unsigned int num_output_neurons = 1;
    const unsigned int num_layers = 3;
    const unsigned int num_hidden_neurons = 9;
    const float desired_error = (const float) 0;
    const unsigned int max_epochs = 500000;
    const unsigned int epochs_between_reports = 1000;

    struct fann *ann = fann_create_standard(num_layers,
                                            num_input_neurons,
                                            num_hidden_neurons,
                                            num_output_neurons);

    fann_set_activation_function_hidden(ann, FANN_SIGMOID_SYMMETRIC);
    fann_set_activation_function_output(ann, FANN_SIGMOID_SYMMETRIC);

    fann_train_on_file(ann,
                       "titanic-training.data",
                       max_epochs,
                       epochs_between_reports,
                       desired_error);

    fann_save(ann, "titanic.net");

    fann_destroy(ann);

    return 0;
}

and the command I'm using to compile and link is:

gcc -Wall -Ifann\src\include titanic-train.c -Lfann\bin -lfanndouble -o titanic-train.exe

The errors I'm getting back are:

C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0x7f): undefined reference to `fann_set_activation_function_hidden'           
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0x93): undefined reference to `fann_set_activation_function_output'           
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0xbf): undefined reference to `fann_train_on_file'                            
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0xd3): undefined reference to `fann_save'                                     
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0xdf): undefined reference to `fann_destroy'                                  
c:/fragileprograms/mingw-native/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o: bad reloc address 0x64 in section `.rdata'                                                                                                                 
c:/fragileprograms/mingw-native/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation                   
collect2.exe: error: ld returned 1 exit status

If I don't link the library at all, I instead get:

C:\Users\kunkelwe\AppData\Local\Temp\ccyOO3jL.o:titanic-train.c:(.text+0x67): undefined reference to `fann_create_standard'
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0x7f): undefined reference to `fann_set_activation_function_hidden'           
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0x93): undefined reference to `fann_set_activation_function_output'           
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0xbf): undefined reference to `fann_train_on_file'                            
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0xd3): undefined reference to `fann_save'                                     
C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o:titanic-train.c:(.text+0xdf): undefined reference to `fann_destroy'                                  
c:/fragileprograms/mingw-native/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: C:\Users\kunkelwe\AppData\Local\Temp\ccsWQg66.o: bad reloc address 0x64 in section `.rdata'                                                                                                                 
c:/fragileprograms/mingw-native/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation                   
collect2.exe: error: ld returned 1 exit status

Edit:

As per Haroogan's request, I ran nm fanndouble.lib. The output is rather extensive, so rather than paste it all here, I've made it available via pastebin here: http://pastebin.com/raw.php?i=vybFhEcX

I'm not familiar with nm, but it appears that the missing symbols do exist in the file.

Edit #2:

The contents of doublefann.h are: http://pastebin.com/mrHKJi8C

and the contents of fann.h, which it includes are: http://pastebin.com/gTrHCYAg

Could the problem just be solved by recompiling the library with MinGW?

Edit #3:

Making the changes that Haroogan suggested worked! In addition to those changes, I had to modify the CMakeLists.txt file for FANN by adding:

if (WIN32)
ADD_DEFINITIONS(-DFANN_DLL_EXPORTS)
endif (WIN32)

Then, running cmake -G "MinGW Makefiles" and then mingw32-make in the root of the project produced a file, libdoublefann.dll, that when linked against and included in the directory of the .exe, allowed me, finally, to run my program.

回答1:

In doublefann.h on the line #116:

#if (_MSC_VER > 1300)

change to:

#if (_MSC_VER > 1300) || defined(__MINGW32__) || defined(__MINGW64__)

Furthermore, on the line #121:

#if defined(_MSC_VER) && (defined(FANN_USE_DLL) || defined(FANN_DLL_EXPORTS))

change to:

#if (defined(_MSC_VER) || defined(__MINGW32__) || defined(__MINGW64__)) && \
    (defined(FANN_USE_DLL) || defined(FANN_DLL_EXPORTS))

来源：https://stackoverflow.com/questions/19286450/link-errors-using-fann

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