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OpenCV and Visual Studio 2010: Infamous namespace error.

This is a discussion on OpenCV and Visual Studio 2010: Infamous namespace error. within the C++ Programming forums, part of the General Programming Boards category; I have tried and compile the following code with out any success, I am using Visual Studio 2010. Code: #include ...

  1. #1
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    OpenCV and Visual Studio 2010: Infamous namespace error.

    I have tried and compile the following code with out any success, I am using Visual Studio 2010.

    Code:
    #include <cxcore.h>
    #include <highgui.h>
    #include <cv.hpp>
    #include <iostream>
    
    
    using namespace cv;
    using namespace std; 
    
    
    int main( int argc, char** argv )
    { 
        if( argc != 2) 
        {
         cout <<" Usage: display_image ImageToLoadAndDisplay" << endl;
         return -1;
        }
        
        Mat image;
        image = imread(argv[1], CV_LOAD_IMAGE_COLOR);   // Read the file
    
    
        if(! image.data )                              // Check for invalid input
        {
            cout <<  "Could not open or find the image" << std::endl ;
            return -1;
        }
    
    
        namedWindow( "Display window", CV_WINDOW_AUTOSIZE );// Create a window for display.
        imshow( "Display window", image );                   // Show our image inside it.
    
    
        waitKey(0);                                          // Wait for a keystroke in the window
        return 0;
    }
    I get the following errors when I try to compile the code.

    \documents\visual studio 2010\projects\test_open_cv.cpp(6): error C2871: 'cv' : a namespace with this name does not exist
    \documents\visual studio 2010\projects\test_open_cv.cpp(17): error C2065: 'Mat' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(17): error C2146: syntax error : missing ';' before identifier 'image'
    \documents\visual studio 2010\projects\test_open_cv.cpp(17): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(18): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(18): error C3861: 'imread': identifier not found
    \documents\visual studio 2010\projects\test_open_cv.cpp(20): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(20): error C2228: left of '.data' must have class/struct/union
    1> type is ''unknown-type''
    \documents\visual studio 2010\projects\test_open_cv.cpp(26): error C3861: 'namedWindow': identifier not found
    \documents\visual studio 2010\projects\test_open_cv.cpp(27): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(27): error C3861: 'imshow': identifier not found
    \documents\visual studio 2010\projects\test_open_cv.cpp(29): error C3861: 'waitKey': identifier not found


    I don't know why I'm getting this. Why am I getting errors for stuff already included in header files. Why am I getting the namespace not defined even though header for it is included for CV.

    Thanks,

    James

  2. #2
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    I don't have a Windows machine handy to test with, but where did you ever read any mention of a "namespace cv"? And where did you find "cv.hpp"?

    Try
    Code:
    #include <cv.h>
    #include <cxcore.h>
    #include <highgui.h>
    #include <iostream>
    using namespace std; 
    
    
    int main( int argc, char** argv )
    { 
    //...
    Maybe you'll find this opencv wiki helpful.

  3. #3
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    Okay I have tried that and now these are the errors I'm getting:


    \documents\visual studio 2010\projects\test_open_cv.cpp(15): error C2065: 'Mat' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(15): error C2146: syntax error : missing ';' before identifier 'image'
    \documents\visual studio 2010\projects\test_open_cv.cpp(15): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(16): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(16): error C3861: 'imread': identifier not found
    \documents\visual studio 2010\projects\test_open_cv.cpp(18): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(18): error C2228: left of '.data' must have class/struct/union
    1> type is ''unknown-type''
    \documents\visual studio 2010\projects\test_open_cv.cpp(24): error C3861: 'namedWindow': identifier not found
    \documents\visual studio 2010\projects\test_open_cv.cpp(25): error C2065: 'image' : undeclared identifier
    \documents\visual studio 2010\projects\test_open_cv.cpp(25): error C3861: 'imshow': identifier not found
    \documents\visual studio 2010\projects\test_open_cv.cpp(27): error C3861: 'waitKey': identifier not found
    1>
    1>Build FAILED.
    1>

  4. #4
    the hat of redundancy hat nvoigt's Avatar
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    You need to learn how to solve problems by yourself:

    Why is Mat undeclared? Google says it's in the namespace cv.
    Why didn't you "use" the namespace cv? Because you were told so and did without questioning.
    Why didn't it compile with the namespace? Google says you included the wrong header file.

    Try to come up with the same answers using a search engine. Then test them.
    hth
    -nv

    She was so Blonde, she spent 20 minutes looking at the orange juice can because it said "Concentrate."

    When in doubt, read the FAQ.
    Then ask a smart question.

  5. #5
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    Actually, I have tried using it without namespace, prior to not being told to do so. However, I wanted to show what would happend if I didn't use namespace cv. And I have been using the google search engine for any problems I have ran into, including this issue.
    However, I had a hard time finding the solution. It seems to me that, I have been inquiring the wrong questions in the search engine and probably why I wasn't able to find the answer I was seeking.
    Thank you, I'll look into using correct header file.

  6. #6
    Registered User hk_mp5kpdw's Avatar
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    According to this page, you should be including cv.h and using namespace cv.
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    Salem likes this.
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