undeclared indentifier opencv cvCaptureFromCAM and cvQueryFrame

Question

I'm pretty new to openCv and C++ in general.

I cannot undestand why I get a undeclared identifier on the cvCaptureFromCAM and from cvQueryFrame

Do you get this type of error when the function is not included into a library? If so, aren't these two functions included into those i include?

My code is

#include "opencv2/objdetect/objdetect.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include <iostream>
#include <stdio.h>

using namespace std;
using namespace cv;

 /** Function Headers */
 void detectAndDisplay( Mat frame );

  /** Global variables */
  String face_cascade_name = "haarcascade_frontalface_alt.xml";
  String eyes_cascade_name = "haarcascade_eye_tree_eyeglasses.xml";
  CascadeClassifier face_cascade;
  CascadeClassifier eyes_cascade;
  string window_name = "Capture - Face detection";
  RNG rng(12345);

  /** @function main */
  int main( int argc, const char** argv )
  {
    CvCapture* capture;
    Mat frame;

    //-- 1. Load the cascades
    if( !face_cascade.load( face_cascade_name ) ){ printf("--(!)Error      loading\n"); return -1; };    //carica nome face_cascade &      eyes_cascade da file xml in CascadeClassifier
    if( !eyes_cascade.load( eyes_cascade_name ) ){ printf("--(!)Error      loading\n"); return -1; };

    //-- 2. Read the video stream
    capture = cvCaptureFromCAM(-1); //legge da camera
    if( capture )
    {
      while( true )
      {
    frame = cvQueryFrame( capture ); //assegna frame

    //-- 3. Apply the classifier to the frame
        if( !frame.empty() )
        { detectAndDisplay( frame ); }
        else
        { printf(" --(!) No captured frame -- Break!"); break; }

        int c = waitKey(10);
        if( (char)c == 'c' ) { break; }
       }
    }
    return 0;
  }

 /** @function detectAndDisplay */
 void detectAndDisplay( Mat frame ) //Mat is the struct that divides      image in 24x24
 {
     //able to store a single instance of  primitive data type is Vec.      Multiple instances Vec can be stored in std::vector, Mat
   std::vector<Rect> faces; //creates rectangular conteiner of info of      faces
   Mat frame_gray; //creates mat container of std vec

   cvtColor( frame, frame_gray, CV_BGR2GRAY ); //void           cvtColor(InputArray src, OutputArray dst, int code, int dstCn=0 ) Converts an image from one color space to another
  equalizeHist( frame_gray, frame_gray );   
 face_cascade.detectMultiScale( frame_gray, faces, 1.1, 2, 0|CV_HAAR_SCALE_IMAGE, Size(30, 30) ); 
 for( size_t i = 0; i < faces.size(); i++ )
 {
    Point center( faces[i].x + faces[i].width*0.5, faces[i].y + faces[i].height*0.5 ); //define center for each investigated area
   ellipse( frame, center, Size( faces[i].width*0.5, faces[i].height*0.5), 0, 0, 360, Scalar( 255, 0, 255 ), 4, 8, 0 );

   Mat faceROI = frame_gray( faces[i] );
   std::vector<Rect> eyes;

   //-- In each face, detect eyes
   eyes_cascade.detectMultiScale( faceROI, eyes, 1.1, 2, 0 |CV_HAAR_SCALE_IMAGE, Size(30, 30) );

   for( size_t j = 0; j < eyes.size(); j++ )
    {
       Point center( faces[i].x + eyes[j].x + eyes[j].width*0.5, faces[i].y + eyes[j].y + eyes[j].height*0.5 );
   int radius = cvRound( (eyes[j].width + eyes[j].height)*0.25 );
   circle( frame, center, radius, Scalar( 255, 0, 0 ), 4, 8, 0 );
 }
 }
  //-- Show what you got
   imshow( window_name, frame );
}

Please remove the duplicate tag because the question regarding the identifier was a small part of it and I was just asking to be sure of something I already new more or less...