Must the int main() function return a value in all compilers?
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在C ++中，在C99和C11中，如果控制流到达main函数的末尾，则语言的特殊规则是，函数impliclty返回0 。
In C++ and C99/C11, without a return statement in main function, it's default to return 0 ;
§ 3.6.1 Main function
A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing return 0;
also read wiki page C/C++ main function
In case a return value is not defined by the programmer, an implicit return 0; at the end of the main() function is inserted by the compiler; this behavior is required by the C++ standard.
main must return an int , some compilers, including Turbo C++, may allow other return values, notably void main , but it's wrong, never use that.
However in C++, if you don't explicitly return a value in main , it's the same as return 0;
C++11 §3.6.1 Main function section 5
A return statement in main has the effect of leaving the main function (destroying any objects with automatic storage duration) and calling std::exit with the return value as the argument. If control reaches the end of main without encountering a return statement, the effect is that of executing
return 0;
Note that for C, this is only supported in C99 and later, but not supported by C89.
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