What happens if main() does not return an int value?

Question

I know that in C compilers the main() function is called by the _start() function which has code something like this:

exit(main());         


        

Answer 1

The function will return an implementation-defined value. For example, in C++, main implicitly returns 0. In this case of a void main then this would simply be returned by _start. However, there are virtually no implementations that would allow any arbitrary return type- it's baked into the operating system that a process exits with an integral value.