drop C-API sample code

modules/core/include/opencv2/core/mat.hpp

@@ -614,12 +614,11 @@ Note that `M.step[i] >= M.step[i+1]` (in fact, `M.step[i] >= M.step[i+1]*M.size[
 that 2-dimensional matrices are stored row-by-row, 3-dimensional matrices are stored plane-by-plane,
 and so on. M.step[M.dims-1] is minimal and always equal to the element size M.elemSize() .
 
-So, the data layout in Mat is fully compatible with CvMat, IplImage, and CvMatND types from OpenCV
-1.x. It is also compatible with the majority of dense array types from the standard toolkits and
-SDKs, such as Numpy (ndarray), Win32 (independent device bitmaps), and others, that is, with any
-array that uses *steps* (or *strides*) to compute the position of a pixel. Due to this
-compatibility, it is possible to make a Mat header for user-allocated data and process it in-place
-using OpenCV functions.
+So, the data layout in Mat is compatible with the majority of dense array types from the standard
+toolkits and SDKs, such as Numpy (ndarray), Win32 (independent device bitmaps), and others,
+that is, with any array that uses *steps* (or *strides*) to compute the position of a pixel.
+Due to this compatibility, it is possible to make a Mat header for user-allocated data and process
+it in-place using OpenCV functions.
 
 There are many different ways to create a Mat object. The most popular options are listed below:
 
@@ -704,10 +703,6 @@ sub-matrices.
         Mat M = Mat(3, 3, CV_64F, m).inv();
     @endcode
     .
-    Partial yet very common cases of this *user-allocated data* case are conversions from CvMat and
-    IplImage to Mat. For this purpose, there is function cv::cvarrToMat taking pointers to CvMat or
-    IplImage and the optional flag indicating whether to copy the data or not.
-    @snippet samples/cpp/image.cpp iplimage
 
 - Use MATLAB-style array initializers, zeros(), ones(), eye(), for example:
 @code
@@ -1641,13 +1636,6 @@ public:
     */
     Mat operator()(const std::vector<Range>& ranges) const;
 
-    // //! converts header to CvMat; no data is copied
-    // operator CvMat() const;
-    // //! converts header to CvMatND; no data is copied
-    // operator CvMatND() const;
-    // //! converts header to IplImage; no data is copied
-    // operator IplImage() const;
-
     template<typename _Tp> operator std::vector<_Tp>() const;
     template<typename _Tp, int n> operator Vec<_Tp, n>() const;
     template<typename _Tp, int m, int n> operator Matx<_Tp, m, n>() const;