178
If the return type of the main function is a type
compatible with int, a return from the initial
call to the main function is equivalent to calling
the exit function with the value returned by the
main function as its argument;10)
179
reaching the } that terminates the
main function returns a value of 0.
180
If the return type is not compatible with int, the
termination status returned to the host environment is unspecified.
181Forward references:
definition of terms (7.1.1), the exit function
(7.20.4.3).