Follow these steps:
1) Open your cmd
2) Type cd.. to change directory to c:drive or cd desktop to change directory.
3)Now type code in cmd:
4) Write some data and save it.
5) Now check that file filename.txt you will not see any text in that file.
6) If you want to see the containts in file the again open cmd and type same command
notepad filename.txt:hidden and press enter...
Now all done and you can see the containts of that file