What is difference between include directive and using directive? Using directive is appropriate or namespace directive

Answer 1

"using" is for c#.
It is equivalent to the "import" of Java and the "include" of C/C++.

Answer 2

"using" is for c#.
It is equivalent to the "import" of Java and the "include" of C/C++.

Answer 3

"using" is for c#.
It is equivalent to the "import" of Java and the "include" of C/C++.