title: what size_t ,flags,host_ptr with a example in detail description as how to take size and what size should be considered?
body: <pre><code>cl_mem clCreateBuffer ( cl_context context,
  cl_mem_flags flags,
  size_t size,
  void *host_ptr,
  cl_int *errcode_ret)
  </code></pre>
  
  <p>here what *host ptr refers to ?</p>