Question

What is the difference between Send Message and Post Message ( in terms of pure windows programming) and how these relate to C# ,WPF and Pure windows programming?

I am new to Threading and all related stuff so please excuse me for obvious quesiton .
I need to dig out the externals of Threading .. Please let me know the links that help me to build my concept from win32 programming to WPF.

I need to underderstand from Post message to Afx ( call to start a new thread ) to delegate Invok/Begin Invoke to Dispatcher.

Answer 1

PostMessage (in “pure windows programming”, aka win32 API) is asynchronous, i.e., to quote the docs:

Places (posts) a message in the
message queue associated with the
thread that created the specified
window and returns without waiting for
the thread to process the message.

To post a message in the message queue
associated with a thread, use the
PostThreadMessage function.

SendMessage is synchronous, that is, again quoting:

Sends the specified message to a
window or windows. The SendMessage
function calls the window procedure
for the specified window and does not
return until the window procedure has
processed the message.

To send a message and return
immediately, use the
SendMessageCallback or
SendNotifyMessage function. To post a
message to a thread’s message queue
and return immediately, use the
PostMessage or PostThreadMessage
function.

A good tutorial on these two functions and their use is here.

The connection to WPF is discussed in this SO question.