How to use cout and cin in C language?

Answer 1

there's no cin or cout in C because the header file iostream was introduced in c++.
use scanf and printf instead in the header file stdio.h

Answer 2

than you

Answer 3

np ☺

Answer 4

cin and cout aren't applicable to c language because of the conflicting header statement .if using c use printf in place of cout and scanf for cin.