why dont we use #include<stdio. h>or conio. h as headers here and why read line write line instead of printf and scanf?

Answer 1

Because C# is not C?

Answer 2

From what I understand, C# is like a combination of Java and C/C++. The syntax is very similar to Java with a few elements of C/C++ mixed in.

Answer 3

It is to show/maintain uniqueness in the Language.