is not and never has been C++, nor has it even been C. See the ISO C++ standard 3.6.1 or the ISO C standard 126.96.36.199.1. A conforming implementation accepts
A conforming implementation may provide more versions of main(), but they must all have return type int. The int returned by main() is a way for a program to return a value to “the system” that invokes it. On systems that doesn’t provide such a facility the return value is ignored, but that doesn’t make “void main()” legal C++ or legal C. Even if your compiler accepts “void main()” avoid it, or risk being considered ignorant by C and C++ programmers.
In C++, main() need not contain an explicit return statement. In that case, the value returned is 0, meaning successful execution. For example:
Note also that neither ISO C++ nor C99 allows you to leave the type out of a declaration. That is, in contrast to C89 and ARM C++ ,”int” is not assumed where a type is missing in a declaration. Consequently:
is an error because the return type of main() is missing.
To summarize above, it is never a good idea to use “void main()” or just “main()” as it doesn’t confirm standards. It may be allowed by some compilers though.