warning: incompatible implicit declaration of built-in function 'lrint'

savio · 07-29-2015, 12:21 PM

Hi,

I want to compile an opencv program on the Linux machine below:

Code:

sav@machine:/shared/sav/test$ uname -a
Linux machine 2.6.32-24-generic #43-Ubuntu SMP Thu Sep 16 14:58:24 UTC 2010 x86_64 GNU/Linux

My gcc command is the following:

Code:

gcc -I/shared/sav/opt/include -L/shared/sav/opt/lib -lopencv_core -lopencv_highgui -lopencv_imgproc -lm imagefilter.c -o imagefilter

After I run the program, I have the following warning:

Code:

In file included from /shared/sav/opt/include/opencv2/core/core_c.h:47,
                 from /shared/sav/opt/include/opencv/cv.h:63,
                 from imagefilter.c:1:
/shared/sav/opt/include/opencv2/core/types_c.h: In function 'cvRound':
/shared/sav/opt/include/opencv2/core/types_c.h:327: warning: incompatible implicit declaration of built-in function 'lrint'

How can I fix this warning?

firstfire · 07-29-2015, 12:53 PM

Hi.

Try to move '-lm' before other libraries in the gcc command line.

EDIT: No. You should add #include <math.h> somewhere..

EDIT2: In the example C program from here there is abovementioned line just before cv.h:

Code:

////////////////////////////////////////////////////////////////////////
//
// hello-world.cpp
//
// This is a simple, introductory OpenCV program. The program reads an
// image from a file, inverts it, and displays the result. 
//
////////////////////////////////////////////////////////////////////////
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <cv.h>
#include <highgui.h>


int main(int argc, char *argv[])
{
  IplImage* img = 0; 
  int height,width,step,channels;
  uchar *data;
  int i,j,k;

  if(argc<2){
    printf("Usage: main <image-file-name>\n\7");
    exit(0);
  }

  // load an image  
  img=cvLoadImage(argv[1]);
  if(!img){
    printf("Could not load image file: s\n",argv[1]);
    exit(0);
  }

  // get the image data
  height    = img->height;
  width     = img->width;
  step      = img->widthStep;
  channels  = img->nChannels;
  data      = (uchar *)img->imageData;
  printf("Processing a %dx%d image with %d channels\n",height,width,channels); 

  // create a window
  cvNamedWindow("mainWin", CV_WINDOW_AUTOSIZE); 
  cvMoveWindow("mainWin", 100, 100);

  // invert the image
  for(i=0;i<height;i++) for(j=0;j<width;j++) for(k=0;k<channels;k++)
    data[i*step+j*channels+k]=255-data[i*step+j*channels+k];

  // show the image
  cvShowImage("mainWin", img );

  // wait for a key
  cvWaitKey(0);

  // release the image
  cvReleaseImage(&img );
  return 0;
}