Is it necessary to write void main(void) ?

Answer 1

http://www.stroustrup.com/bs_faq2.html#void-main

Answer 2

No, as the default signature for main is :

int main(char argc, char** argv)
{

}

But, you may use :

int main()
{

}

Other versions are not allowed. Eg char main(), string main(), etc. in C++.

Answer 3

no

Answer 4

no need