question

[paupau]

why can i use using namespace std; when i can run .....! have an error....? for using namespace std; ..?

[hamsterman]

Try writing sentences that make sense. If something doesn't compile, post the code and the error message.

[paupau]

what is the function of using namespace std; ...?

[graham sullivan]

the standard namespace allows you to use the cout and cin streams and the string class as well as others. You could do std::cout << var; without using namespace std.

[TheMassiveChipmunk]

Do you have

#included <iostream>
or
#included <fstream>
or
#included <sstream> 

In your code?