opencv 读取usb（uvc）摄像头和显示 c++

#include 
#include 

using namespace std;
using namespace cv;

int main()
{

    VideoCapture camera(0)

    if(!camera.isOpened())
    {

       std::cout<<"The camera is not turned on!!!"<> frame;

	if(frame.empty())
            break
        else
        {
            imshow("test",frame);
         }
return 0;
 }