Could somebody give me some examples of open a serial communication between the PC and the Microcontroller using C++?

I need to program an user interface that send commands to the microcontroller using the serial interface but I have to make my own program to communicate the pc and the microcontroller.

(Without using Terminal programs, like Tera Term, etc.)

This is exactly the same question I was about to post?  I'm a Newbie and I see examples of printf() in a bunch of code examples but I do not know how or where these messages go?  I too want to communicate back and forth with mbed using C# but I cannot find an example of how this is done...

Found it...

http://mbed.org/handbook/SerialPC

You may find this useful:-

Especially look at example2.cpp which demonstrates a serial messaging design. It won't help you write a C#/C++/VB/other host program but it will probably make the Mbed end of things a lot more simple.