Compiler does not recognize OpenCV library - c++

Question

I am using Visual studio 2013 and opencv 3.0.0.
I would like to run this code:
#include <opencv\cv.h>
#include <opencv\highgui.h>
using namespace cv;
int main(){
//Generate matrix to store image
Mat image;
//initialize capture
VideoCapture cap;
cap.open(0);
//Create window to show image
namedWindow("window", 1);
while (1){
//copy webcam stream to image
cap >> image;
//print image to screen
imshow("window", image);
//delay 33ms
waitKey(33);
}
}
However, I got the following errors:
first.cpp(12): error C2065: 'VideoCapture' : undeclared identifier
1>first.cpp(12): error C2146: syntax error : missing ';' before identifier 'cap'
1>first.cpp(12): error C2065: 'cap' : undeclared identifier
1>first.cpp(13): error C2065: 'cap' : undeclared identifier
1>first.cpp(13): error C2228: left of '.open' must have class/struct/union
1> type is 'unknown-type'
1>first.cpp(16): error C3861: 'namedWindow': identifier not found
1>first.cpp(20): error C2065: 'cap' : undeclared identifier
1>first.cpp(23): error C3861: 'imshow': identifier not found
1>first.cpp(26): error C3861: 'waitKey': identifier not found
1>
1>Build FAILED.
I linked the library conveniently. The compiler receives the opencv library. However, it gives such errors.