Why write using namespace std Even program execute without it and when we use it gives error please explain

Answer 1

if you do not use the namespace you can do it like this
std:cout<<"hello world";
with std you can only put cout

Answer 2

it depends. in turbo c we do not need to write using namespace std. but in dev c we need to mention it. but in dev c we should not write void before the main prog. eg.
void main ( ) gives error
main ( ) doesnot

Answer 3

how to program simple games

Answer 4

If you use using namespace std; basicly means a time saver so you don't have the write std::cout every time. Or for anything that requires std::. So you can not use the namespace but you'll be writing a lot more code then you need too. Remember K.I.S.S. Keep it simple stupid.