What is output handling function?

I hope this is not for some kind of a college assignment. It would help us if you ask a bit detailed question, so that we know what exactly are you trying to find out.

Here's a little explanation of I/O handling functions -
The I/O library subroutines can send data to or from either devices or files. The system treats devices as if they were I/O files. For example, you must also open and close a device just as you do a file. For eg: - fopen() and fclose().

Fopen() - Opens the file whose name is specified in the parameter filename and associates it with a stream that can be identified in future operations by the #-Link-Snipped-# pointer returned.

in case of files, i agree with #-Link-Snipped-#
but if it is not for files, then the output handling or manipulating functions are used to display your outputs in a proper way. In c++, such functions are in iomanip.h
like setw(), setprecision() etc etc.