Discussion :

[JackieMIF]

Bonjour,

est ce que quelqu'un peu m'expliquer lq methode à effectuer pour corriger ce genre d'erreurs dans Visual Studio :

error C2871: 'cv' : a namespace with this name does not exist

Merci

[oodini]

Faudrait que tu mettes la ligne de code sur laquelle pointe l'erreur.

[JackieMIF]

C'est la ligne juste après les includes

Code :

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#include <cv.h>
#include <highgui.h>
#include <math.h>
#include "stdafx.h"
 
using namespace cv;
 
int main(int argc, char** argv)
{
    Mat img, gray;
    if( argc != 2 && !(img=imread(argv[1], 1)).data)
        return -1;
    cvtColor(img, gray, CV_BGR2GRAY);
    // smooth it, otherwise a lot of false circles may be detected
    GaussianBlur( gray, gray, Size(9, 9), 2, 2 );
    vector<Vec3f> circles;
    HoughCircles(gray, circles, CV_HOUGH_GRADIENT,
                 2, gray->rows/4, 200, 100 );
    for( size_t i = 0; i < circles.size(); i++ )
    {
         Point center(cvRound(circles[i][0]), cvRound(circles[i][1]));
         int radius = cvRound(circles[i][2]);
         // draw the circle center
         circle( img, center, 3, Scalar(0,255,0), -1, 8, 0 );
         // draw the circle outline
         circle( img, center, radius, Scalar(0,0,255), 3, 8, 0 );
    }
    namedWindow( "circles", 1 );
    imshow( "circles", img );
    return 0;
}

[oodini]

Je suppose que l'espace de nom cv n'est défini dans aucun des .h...

[JackieMIF]

Et voilà le rapport d'erreur

Code :

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1>------ Rebuild All started: Project: hough, Configuration: Release Win32 ------
1>Build started 11.07.2012 17:09:55.
1>_PrepareForClean:
1>  Deleting file "Release\hough.lastbuildstate".
1>InitializeBuildStatus:
1>  Touching "Release\hough.unsuccessfulbuild".
1>ClCompile:
1>  stdafx.cpp
1>d:\entwicklung\opencv\opencv-2.4.0\opencv\modules\flann\include\opencv2\flann\logger.h(66): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
1>          C:\Programme\Microsoft Visual Studio 10.0\VC\include\stdio.h(234) : see declaration of 'fopen'
1>  hough.cpp
1>hough.cpp(1): warning C4627: '#include <cv.h>': skipped when looking for precompiled header use
1>          Add directive to 'StdAfx.h' or rebuild precompiled header
1>hough.cpp(2): warning C4627: '#include <highgui.h>': skipped when looking for precompiled header use
1>          Add directive to 'StdAfx.h' or rebuild precompiled header
1>hough.cpp(3): warning C4627: '#include <math.h>': skipped when looking for precompiled header use
1>          Add directive to 'StdAfx.h' or rebuild precompiled header
1>hough.cpp(6): error C2871: 'cv' : a namespace with this name does not exist
1>hough.cpp(10): error C2065: 'Mat' : undeclared identifier
1>hough.cpp(10): error C2146: syntax error : missing ';' before identifier 'img'
1>hough.cpp(10): error C2065: 'img' : undeclared identifier
1>hough.cpp(10): error C2065: 'gray' : undeclared identifier
1>hough.cpp(11): error C2065: 'img' : undeclared identifier
1>hough.cpp(11): error C2228: left of '.data' must have class/struct/union
1>hough.cpp(11): error C3861: 'imread': identifier not found
1>hough.cpp(13): error C2065: 'img' : undeclared identifier
1>hough.cpp(13): error C2065: 'gray' : undeclared identifier
1>hough.cpp(13): error C2065: 'CV_BGR2GRAY' : undeclared identifier
1>hough.cpp(13): error C3861: 'cvtColor': identifier not found
1>hough.cpp(15): error C2065: 'gray' : undeclared identifier
1>hough.cpp(15): error C2065: 'gray' : undeclared identifier
1>hough.cpp(15): error C3861: 'GaussianBlur': identifier not found
1>hough.cpp(15): error C3861: 'Size': identifier not found
1>hough.cpp(16): error C2065: 'vector' : undeclared identifier
1>hough.cpp(16): error C2065: 'Vec3f' : undeclared identifier
1>hough.cpp(16): error C2065: 'circles' : undeclared identifier
1>hough.cpp(17): error C2065: 'gray' : undeclared identifier
1>hough.cpp(17): error C2065: 'circles' : undeclared identifier
1>hough.cpp(17): error C2065: 'CV_HOUGH_GRADIENT' : undeclared identifier
1>hough.cpp(18): error C2065: 'gray' : undeclared identifier
1>hough.cpp(18): error C2227: left of '->rows' must point to class/struct/union/generic type
1>          type is ''unknown-type''
1>hough.cpp(17): error C3861: 'HoughCircles': identifier not found
1>hough.cpp(19): error C2065: 'circles' : undeclared identifier
1>hough.cpp(19): error C2228: left of '.size' must have class/struct/union
1>          type is ''unknown-type''
1>hough.cpp(21): error C2065: 'Point' : undeclared identifier
1>hough.cpp(21): error C2146: syntax error : missing ';' before identifier 'center'
1>hough.cpp(21): error C2065: 'circles' : undeclared identifier
1>hough.cpp(21): error C2065: 'circles' : undeclared identifier
1>hough.cpp(21): error C3861: 'center': identifier not found
1>hough.cpp(21): error C3861: 'cvRound': identifier not found
1>hough.cpp(21): error C3861: 'cvRound': identifier not found
1>hough.cpp(22): error C2065: 'circles' : undeclared identifier
1>hough.cpp(22): error C3861: 'cvRound': identifier not found
1>hough.cpp(24): error C2065: 'img' : undeclared identifier
1>hough.cpp(24): error C2065: 'center' : undeclared identifier
1>hough.cpp(24): error C3861: 'circle': identifier not found
1>hough.cpp(24): error C3861: 'Scalar': identifier not found
1>hough.cpp(26): error C2065: 'img' : undeclared identifier
1>hough.cpp(26): error C2065: 'center' : undeclared identifier
1>hough.cpp(26): error C3861: 'circle': identifier not found
1>hough.cpp(26): error C3861: 'Scalar': identifier not found
1>hough.cpp(28): error C3861: 'namedWindow': identifier not found
1>hough.cpp(29): error C2065: 'img' : undeclared identifier
1>hough.cpp(29): error C3861: 'imshow': identifier not found
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:01.95
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========

[JackieMIF]

Et donc comment est il possible de le definir?

[oodini]

Commence par déplacer la ligne

Code :

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#include "stdafx.h"

avant toute autre directive d'inclusion.

[Arzar]

C'est un problème de header précompilé.
Lorsque les headers précompilés sont activés, sous Visual Studio, tous les fichiers .cpp doivent obligatoirement commencer par #include "stdafx.h". Toutes les lignes précédant #include "stdafx.h" sont purement et simplement ignorées, donc par exemple ici #include <cv.h> etc.


C'est ce que dit le message d'erreur :

'#include <cv.h>': skipped when looking for precompiled header use
1> Add directive to 'StdAfx.h' or rebuild precompiled header