I am working on to the alfresco 4.2 community addition.now i have to use the some kind of Scanning feature to scan the hard copy of the document and upload.
Yes it looks like you are looking for some OCR features in Alfresco. There is no OCR feature available out of box you need to integrate alfresco with third party OCR tool like kofax. Alfresco readily provide support for integration with most of the famous OCR tools.