Code:
system("cls");

Advantages:       None really.

Disadvantages:  Spawns a process to do the dirty work for you.
It's bad for security reasons. 
For example, someone could map cls to another program, and yours would run it without realising.
I use system("cls") and it seems to work perfectly.
Does the word "someone" or a program that is
already existing on your computer?
Even so, what could be so bad about the system clearing the screen on accident?