If you want examples of main () calling main (), here are plenty: ioccc.org It's the website of the International Obfuscated C Code Contest, and folding everything into a single function called main is an effective obfuscation technique. In Turbo C , void main () will be accepted, whereas in dev-cpp main () should return a value. 3.return 0 simply exits the program with exit status 0 , in other words the return value determines the exit status of the main thread. If you are trying to close a question where someone should be using this idiom and isn't, consider closing as a duplicate of Why is Python running my module when I import it, and how do I stop it? instead. For questions where someone simply hasn't called any functions, or incorrectly expects a function named main to be used as an entry point automatically, use Why doesn't the main () function run when I start a Python script? Where does the script start running?. The Python approach to " main " is almost unique to the language ("). The semantics are a bit subtle. The __name__ identifier is bound to the name of any module as it's being imported. However, when a file is being executed then __name__ is set to "__main__" (the literal string: __main__). This is almost always used to separate the portion of code which should be executed from the portions of code which define functionality. So Python code often contains a line like: #!/usr/bin/env python from ...
