_tmain () why such a name?

It's simple.

For non-Unicode programs, the standard name main and the argument list int argc, char* argv[] .

For Unicode programs, the list of parameters in MSVC looks like int argc, wchar_t* argv[] , and to avoid conflicts with source codes and compilers that meet the standard, the function is called wmain .

For programs that can be compiled both in Unicode- and non-Unicode-mode, the argument list looks like int argc, _TCHAR* argv[] , where the _TCHAR macro _TCHAR defined as char or wchar_t depending on the value of the _UNICODE macro. Thus, you need a third name for the function. So it was coined the name _tmain .

All this, of course, requires some linker magic, which should be able to determine the entry point not only in the main function, as in the standard, but also in the wmain / _tmain .

If you are sure that you do not need a Unicode application, you can rename the function to main and give it a list of arguments int argc, char* argv[] to conform to the standard. Or if you firmly decided that your program will run only under the WinNT / XP / 7 line (and not Win95 / 98), you can stop at the Unicode version and rename the function to wmain (respectively, the arguments should be int argc, wchar_t* argv[] ).

Late clarification (thanks @alexolut): According to the documentation , _tmain is defined in <tchar.h> using typedef as main or wmain , so your program will still have either main or wmain .

(And yes, you can omit the parameters, or add the third parameter envp , or declare the return type void .)