A callback function is a function that you write that could be called by outside code (i.e. by windows functions).  You set up a callback function by passing the address of your function to the API from which your callback is referenced.

For example, I want my application to handle runtime exceptions rather than letting C++ runtime take care of things for me.  So I wrote a function called my_exception_handler(int, EXCEPTION_POINTERS*) and I call a Microsoft function called _set_se_translator and pass it the address of my_exception_handler.  

In the example above, my_exception_handler is a callback function -- I will never call it myself, but I pass the address of it to an API that will cause it to possibly be called.

Hope that helps!

Pat Gleason
gleason@megsinet.net

its basically a Function pointer, it points to a function in memory, can be used inside and outside of a programming language some languagues cannot use callback functions from say VC++, like visual basic cant(unless you use an API by another dll and such)

Karl
kb244@kb244.8m.com

Experienced in , or have messed with : VC++, Borland C++ Builder, VJ++6(starting),VB-Dos, VB1 thru VB6, Delphi 3 pro, Borland C++ 3(DOS), Borland C++ 4.5, HTML,Visual InterDev 6, ASP(WebProgramming), QBasic(least i didnt start with COBOL)