Undefined reference

[h4ever]

main.c

#include "types.h"
#include "gaussian.h"
#include "args.h"
#include <stdbool.h>


int main ( int argc, char *argv[] )
{
    double units;
    uint32_t gaussianSize;
    float gaussianSigma;
    char* imgname;//the name of the image file, taken by the arguments

    //read in the program's arguments
    if(readArguments(argc,argv,&imgname,&gaussianSize,&gaussianSigma)==false)
        return -1;


    //perform CPU blurring
    if(pna_blur_cpu(imgname,gaussianSize,gaussianSigma)==false)//time it
        return -2;

    //perform GPU blurring and then read the timer
    if(pna_blur_gpu(imgname,gaussianSize,gaussianSigma)==false)
        return -3;

    return 0;
}

I have errors of undefined reference for functions
readArguments declared in args.h
pna_blur_cpu declared in gaussian.h
pna_blur_gpu declared in gaussian.h
can you tell me why?

[kevinkjt2000]

Could you show args.h to us?

[h4ever]

#ifndef READ_ARGS_H
#define READ_ARGS_H

#include "types.h"
#include "refu/rf_setup.h"

extern char helpStr[];

#define DEFAULT_IMG_NAME        "image3.BMP"
#define DEFAULT_GAUSSIAN_SIZE   3
#define DEFAULT_GAUSSIAN_SIGMA  0.8

bool readArguments(int argc, char *argv[],char** imgName,uint32_t* gaussianSize,float* gaussianSigma);

#endif 

[keskiverto]

The definition of bool, where is it? types.h?

[kevinkjt2000]

Is this C or C++? Can you give us the exact compiler errors?

[Disch]

'undefined reference' usually means there is no body for the mentioned functions.

In your case... it sounds like you have prototypes for readArguments, pna_blur_cpu, and pna_blur_gpu... but you never gave those functions a body.

[h4ever]

I use C.
types.h
#include <stdbool.h>

Here types.c, there is definition of readArguments:
http://paste.ofcode.org/QE5GYVWU2EarMTwmHYnbDx

Gaussian.h:

#ifndef GAUSSIAN_H
#define GAUSSIAN_H
#include "types.h"
#include "bitmap.h"
#include "refu/rf_setup.h"
char pna_blur_cpu(char* imgname,uint32_t size,float sigma);
char pna_blur_gpu(char* imgname,uint32_t size,float sigma);
#endif 

And here is gaussian.c
http://paste.ofcode.org/3vQCC5h68mQuVFMHgpMzuJ

Errors:

main.cpp|24|undefined reference to `readArguments(int, char**, char**, unsigned int*, float*)'|
main.cpp|31|undefined reference to `pna_blur_cpu(char*, unsigned int, float)'|
main.cpp|40|undefined reference to `pna_blur_gpu(char*, unsigned int, float)'| 

Edit:
there is type uint32_t and I change it to unsigned int ... but it is the same still.

[Disch]

Are those source files part of your project? IE, are you compiling/linking them?

[h4ever]

Yeas, they are part of project. They are included. No linking.

[Disch]

I'm skeptical.

Try mucking up gaussian.c. Like add a garbage line to it just before the includes:

// something like this:

rkljhdkslfj

Then try rebuilding. If you don't get a compiler error, you know the file is not being linked.

[h4ever]

Can you try it? Not to build, just check it. http://sourceforge.net/projects/autots/files/Gaussian_with_OpenCL%201.zip/download Code blocks project Gaussian_with_OpenCL.cbp, it uses OpenCL.

[JLBorges]

> I use C.

Then, how are you getting errors from main.cpp?
main.cpp|31|undefined reference to ...

Either rename the file as main.c

Or wrap the C header in

#ifdef __cplusplus 
    extern "C" {
#endif 

#include "gaussian.h"

#ifdef __cplusplus 
    }
#endif  

Tip: C linkage is not type-safe.

With C you wouldn't have got this error:
undefined reference to `pna_blur_cpu(char*, unsigned int, float)'

Instead, you would have got: undefined reference to `_pna_blur_cpu'

[h4ever]

Wow, I did not noticed that. I had no idea it could be the reason. That's the file I
originally created and copied code into it, instead of copy the original file as main.c . This was the error.

I yet removed two lines of C++ and it looked compiled, but program crashes after run. But never mind. I just wanted to remove this error. I already have updated version of the program which works. Thanks for help.

[ne555]

> Try mucking up gaussian.c.
> Then try rebuilding. If you don't get a compiler error, you know the file is not being linked.
Or you could read the build command


> Instead, you would have got: undefined reference to `_pna_blur_cpu'
¿why would it add an underscore?

[JLBorges]

> ¿why would it add an underscore?

Don't ask me; ask the people who wrote the linker which emitted the symbol verbatim.

Note: It does not 'add an underscore'; the underscore is there in the symbol given to the linker. Some linkers 'remove the leading underscore' when they format the diagnostic; some others do not.