What are the differences between the main() function and other user-defined functions in C?

Question

main()函数在 C 中称为用户定义函数。但它与其他用户定义函数有何不同？

Answer 1

The main() function is just a regular user-defined function — but it has two special properties:

• In a hosted implementation (the normal type), it is the function called by the start-up code.
• In C99 and later, if execution falls off the end of main() without an explicit return statement, it is equivalent to return 0; . No other function gets that privileged treatment.

See also What should main() return in C and C++? for some caveats about the second point.