Should I use exit()
or just return
statements in main()
? Personally I favor the return
statements because I feel it's like reading any other function and the flow control when I'm reading the code is smooth (in my opinion). And even if I want to refactor the main()
function, having return
seems like a better choice than exit()
.
Does exit()
do anything special that return
doesn't?
Actually, there is a difference, but it's subtle. It has more implications for C++, but the differences are important.
When I call return
in main()
, destructors will be called for my locally scoped objects. If I call exit()
, no destructor will be called for my locally scoped objects! Re-read that. exit()
does not return. That means that once I call it, there are "no backsies." Any objects that you've created in that function will not be destroyed. Often this has no implications, but sometimes it does, like closing files (surely you want all your data flushed to disk?).
Note that static
objects will be cleaned up even if you call exit()
. Finally note, that if you use abort()
, no objects will be destroyed. That is, no global objects, no static objects and no local objects will have their destructors called.
Proceed with caution when favoring exit over return.
http://groups.google.com/group/gnu.gcc.help/msg/8348c50030cfd15a
Another difference:
exit
is a Standard Library
function so you need to include
headers and link with the standard
library. To illustrate (in C++),
this is a valid program:
int main() { return 0; }
but to use exit
you'll need an include:
#include <stdlib.h>
int main() { exit(EXIT_SUCCESS); }
Plus this adds an additional assumption: that calling exit
from main
has the same side effects as returning zero. As others have pointed out, this depends on what kind of executable you're building (i.e., who's calling main
). Are you coding an app that uses the C-runtime? A Maya plugin? A Windows service? A driver? Each case will require research to see if exit
is equivalent to return
. IMHO using exit
when you really mean return
just makes the code more confusing. OTOH, if you really do mean exit
, then by all means use it.