A process terminates normally when its program signals it is done by
calling exit. Returning from main is equivalent to
calling exit, and the value that main returns is used as
the argument to exit.
— Function: void exit (int status)
The exit function tells the system that the program is done, which
causes it to terminate the process.
status is the program's exit status, which becomes part of the
process' termination status. This function does not return.
Normal termination causes the following actions:
Functions that were registered with the atexit or on_exit
functions are called in the reverse order of their registration. This
mechanism allows your application to specify its own “cleanup” actions
to be performed at program termination. Typically, this is used to do
things like saving program state information in a file, or unlocking
locks in shared data bases.
All open streams are closed, writing out any buffered output data. See
Closing Streams. In addition, temporary files opened
with the tmpfile function are removed; see Temporary Files.