EXIT_FAILURE vs exit(1)?

exit(1) (usually) indicates unsuccessful termination. However, its usage is non-portable. For example, on OpenVMS, exit(1) actually indicates success.

Only EXIT_FAILURE is the standard value for returning unsuccessful termination, but 1 is used for the same in many implementations.

So to summarize:
If you want to write perfectly portable code use,

EXIT_FAILURE for failure case. While,
You can use either exit(0) or EXIT_SUCCESS for success case.

Note that, EXIT_SUCCESS or 0 are both same.

Reference:

C99 Standard: 7.20.4.3 The exit function
Para 5

Finally, control is returned to the host environment. If the value of status is zero or
EXIT_SUCCESS, an implementation-defined form of the status successful termination is
returned. If the value of status is EXIT_FAILURE, an implementation-defined form
of the status unsuccessful termination is returned. Otherwise the status returned is
implementation-defined.