Update videocapture_basic.cpp

I believe you are using the wrong version of open() on line 28 - adding deviceID + appId together. It's better to use the new version of .open() taking two integers as parameter.

modules/videoio/doc/videoio_overview.markdown

@@ -39,10 +39,10 @@ For example to grab from default camera using Direct Show as backend
 
 ```cpp
 //declare a capture object
-cv::VideoCapture cap(0 + cv::CAP_DSHOW);
+cv::VideoCapture cap(0, cv::CAP_DSHOW);
 
 //or specify the apiPreference with open
-cap.open(0 + cv::CAP_DSHOW);
+cap.open(0, cv::CAP_DSHOW);
 ```
 
 If you want to grab from a file using the Direct Show as backend:

modules/videoio/src/cap_aravis.cpp

@@ -58,7 +58,7 @@
 // Please obvserve, that jumbo frames are required when high fps & 16bit data is selected.
 // (camera, switches/routers and the computer this software is running on)
 //
-// Basic usage: VideoCapture cap(CAP_ARAVIS + <camera id>);
+// Basic usage: VideoCapture cap(<camera id>, CAP_ARAVIS);
 //
 // Supported properties:
 //  read/write

samples/cpp/videocapture_basic.cpp

@@ -25,7 +25,7 @@ int main(int, char**)
     int deviceID = 0;             // 0 = open default camera
     int apiID = cv::CAP_ANY;      // 0 = autodetect default API
     // open selected camera using selected API
-    cap.open(deviceID + apiID);
+    cap.open(deviceID, apiID);
     // check if we succeeded
     if (!cap.isOpened()) {
         cerr << "ERROR! Unable to open camera\n";