corrigé un code source en opencv

    #include "stdafx.h"
    #include <cv.h>
    #include <vector>
    #include <string>
    #include <cxcore.h>
    #include <highgui.h>
    using namespace std;
    int _tmain(int argc, _TCHAR* argv[])
    {
        for (int k=0;k<1;k++)
    {
    std::string varimg;
    char format[] = "franck_000%d.jpg";
    char filename[sizeof format+100];
    sprintf(filename,format,k);
    varimg = filename ;
    IplImage*imgw = cvLoadImage( varimg.c_str() ); 
    cvNamedWindow( "Example1", CV_WINDOW_AUTOSIZE );
    cvRectangle(imgw, cvPoint(230,100),cvPoint(550,500),CV_RGB(255,0,0), 3);
     cvShowImage("Example1",imgw);
        cvWaitKey(1);
    cvReleaseImage(&imgw);
    }
        return 0;
    }

int main()
{
  cvNamedWindow( "Example1", CV_WINDOW_AUTOSIZE );

  char filename[18];
  int n;
  for (n=0; n<100; n++)
  {
    sprintf(filename,"img/frame%04d.jpg", n);
    IplImage*imgw = cvLoadImage(filename, CV_LOAD_IMAGE_COLOR); 
    cvRectangle(imgw, cvPoint(230,100), cvPoint(550,500), CV_RGB(255,0,0),1, CV_AA, 0);
    cvShowImage("Example1",imgw);
    if (cvWaitKey(200)>0) break;
    cvReleaseImage(&imgw);
  }

  return 0;
}

IplImage*imgw = cvLoadImage( etc );
// vérifie que le chargement a réussi
if (!imgw)
{
 puts("cvLoadImage(%s) a echoué\n", filename);
 break;
}