The reason one compiled differently is because different compilers have different standards

now if you look at where you got the error message it actually is not an error message at all

all it is is a warning that states you have a header declared in a non-standard way

your code will still compile and it will still run perfectly fine

however the using namespace std allows for the newer compilers to read

code in basic terms the same as an older compiler

because if you wanted to get incredibly technical if you didn't use the using namespace std

everywhere you typed cout you would have to type std::cout

but not only for cout but everything that the iostream library pulls

so in the end its just helping you out by saving you a little bit of typing

but remember to read the "ERROR MESSAGES" a little first because they aren't always errors

sometimes they are just warnings

if you have anymore questions about this or there is something I didnt cover or you want more info on

just ask

~ Geo

~ Don't take life too seriously, you'll never get out alive!