cmake: require C++11 and CMake 3.5.1+

samples/cpp/example_cmake/CMakeLists.txt

@@ -1,5 +1,9 @@
 # cmake needs this line
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.1)
+
+# Enable C++11
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
 
 # Define project name
 project(opencv_example_project)
@@ -18,11 +22,6 @@ message(STATUS "    version: ${OpenCV_VERSION}")
 message(STATUS "    libraries: ${OpenCV_LIBS}")
 message(STATUS "    include path: ${OpenCV_INCLUDE_DIRS}")
 
-if(CMAKE_VERSION VERSION_LESS "2.8.11")
-  # Add OpenCV headers location to your include paths
-  include_directories(${OpenCV_INCLUDE_DIRS})
-endif()
-
 # Declare the executable target built from your sources
 add_executable(opencv_example example.cpp)