dennis richie made c language with only 32 keywords all the functions and statements are to be created by the programer. if so wher is the source code of "printf" "scanf" "cin" "cout" ?
They're found in the source code of a language implementation. That is, Borland C/C++, Microsoft Visual C++, Dev-C++, gnu, etc. (And the implementation of the C or C++ language may itself not be in C or C++.)
What you get when you use C or C++ is a defined interface that will make available to you a function printf that will behave in a well-defined manner. Whether the actual source of printf is written in C or assembly or Pascal or whatever is not supposed to matter.
Maybe this will help you understand.
Don't be afraid next time of creating a new thread when you want to ask something. People frown upon old threads that get bumped to a current active state.
That one is the GNU C's implementation. I think you probably find your way from there on to scanf. And doing a google on the file name gives more results I bet.
Why not run your code via the debugger and when you get to the printf function step into the function. If on your machine your compiler has the full source code for the libraries (i.e. Win SDK), then you should find the code.