Documentation: application-developer: Add camera detection check

The simple-cam application has a check to ensure that at least one
camera is present before attempting to access the first camera, to avoid
a crash. Update the application developer's guide to match this
behaviour.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/Documentation/guides/application-developer.rst b/Documentation/guides/application-developer.rst
index 41a7d883..cafb24b1 100644
--- a/Documentation/guides/application-developer.rst
+++ b/Documentation/guides/application-developer.rst
@@ -109,10 +109,18 @@ the Camera Manager reports as available to applications.
 Camera devices are stored by the CameraManager in a list accessible by index, or
 can be retrieved by name through the ``CameraManager::get()`` function. The
 code below retrieves the name of the first available camera and gets the camera
-by name from the Camera Manager.
+by name from the Camera Manager, after making sure that at least one camera is
+available.
 
 .. code:: cpp
 
+   if (cm->cameras().empty()) {
+       std::cout << "No cameras were identified on the system."
+                 << std::endl;
+       cm->stop();
+       return EXIT_FAILURE;
+   }
+
    std::string cameraId = cm->cameras()[0]->id();
    camera = cm->get(cameraId);