mainvoid

Mainvoid is a term that occasionally appears in informal programming discussions to describe a main function defined with a void return type, commonly written as void main(). It is not an official name or recognized construct in major programming languages. The term is typically used as a shorthand to discuss non-standard entry point definitions and their consequences rather than to describe a formal feature.

In C and C++, the language standards require the program entry point to be a function named main that returns an int. Although many compilers historically accepted void main, such usage is considered non-portable and ill-formed by the standard. Returning a non-int value or omitting a return statement in main may also yield undefined or implementation-defined behavior. The label mainvoid reflects this non-standard practice rather than a formal capability.

Because mainvoid often appears only in examples or discussions about portability, it serves as a warning about non-conforming code rather than a recommended technique. In teaching contexts, it is used to illustrate why returning int and using appropriate arguments improves portability and interoperability across platforms and toolchains.

Best practice is to define main as int main(void) or int main(int argc, char *argv[]) and to return 0 on success. Developers generally avoid void main and rely on the language standard to ensure consistent program startup behavior. See also main function, C standard, C++ standard, and program entry point in computing references.