错误：标识符“ img”未定义

Question

I'm beginner to openCV. I dowloaded opencv2.4.5 and visual studio express 2012 then i followed this link http://opencv-srf.blogspot.in/2013/05/installing-configuring-opencv-with-vs.html for setup everything in environment variable etc. Then i followed below link http://opencv-srf.blogspot.in/2013/06/load-display-image.html to create sample application. I included proper #include path. But i'm getting error.

#include "stdafx.h"

#include <C:\opencv\build\include\opencv\cv.h>
#include <C:\opencv\build\include\opencv\cxcore.h>
#include <C:\opencv\build\include\opencv\highgui.h>

#include "C:\opencv\build\include\opencv2\highgui\highgui.hpp"
#include <iostream>

using namespace cv;
using namespace std;

int main( int argc, const char** argv )
{
     Mat img = imread("MyPic.JPG", CV_LOAD_IMAGE_UNCHANGED); //read the image data in the file "MyPic.JPG" and store it in 'img'

     if (img.empty()) //check whether the image is loaded or not
     {
          cout << "Error : Image cannot be loaded..!!" << endl;
          //system("pause"); //wait for a key press
          return -1;
     }

     namedWindow("MyWindow", CV_WINDOW_AUTOSIZE); //create a window with the name "MyWindow"
     imshow("MyWindow", img); //display the image which is stored in the 'img' in the "MyWindow" window

     waitKey(0); //wait infinite time for a keypress

     destroyWindow("MyWindow"); //destroy the window with the name, "MyWindow"

     return 0;
}

Answer 1

please do not use an absolute path for the includes, this is totally non-portable.

it should look like this:

// the usual suspects:
#include "opencv2\core\core.hpp"       // Mat is defined here.
#include "opencv2\imgproc\imgproc.hpp"
#include "opencv2\highgui\highgui.hpp"

also, to make this work, your "additional include folders" should point to "opencv/build/include"

and avoid the old c-api headers, like cv.h, highgui.h, cxcore.h