I'm working on a document application and part of this application I've to add support to read the keyboard pressed events and replace the pre-defined characters set if that keyboard entry is match with the pre-defind short form/word.The actual application has implemented in C++.
Please provide me your thoughts on how to implement this. Is there any sample C++ program for reference? algorithm/concepts?
Standard C++ doesn't support keypress events, so you'll have to look at either an OS function, or a framework function. Portable C++ frameworks like wxWidgets or Qt support keypress events on Windows, Mac and Linux.
Learn how to catch the keydown events using wxWidgets api, maybe here: http://docs.wxwidgets.org/stable/wx_eventhandlingoverview.html#eventhandlingoverview pay attention to key events. Implement a switch in C++ to see what key combination was pressed, and set the text to the edit accordingly. What I'm thinking about here is to convert a CTRL-SHIFT-A keypress to a text like Ctrl-Shift-a in a edit box.
If you are thinking of converting a combination of characters to other character, for example kanji or hiragana, the algorithm could be longer and more data structures required.
If you are under Windows you can use the GetAsyncKeystate API call and watch for changes, or use the low-level keyboard hooks (slightly more complicated) (CreateHookEx + related functions).
Under DOS (or possibly Linux) you can use _kbhit in conio.h in console mode, i usually stick this in a loop (while(!_kbhit());) for a "press any key to continue", but using _getch can retrieve the key which was pressed