Can you declare a function in the body of another function in c language?

yes, we can not declare a function in the body of another function. but if we declare a function in the body of another function then we can call that very function only in that particular function in which it is declared; and that declared function is not known to other functions present in your programme. So if a function is required in almost all functions of your programme so you must declare it outside the main function i.e in the beginning of your programme.