Is it necessary to supply the null character when declaring an character's array?

Question

A string constant in C is stored as a character array, while creating such an array element by element, is it necessary to supply the null character.

I need to store

Answer 1

No, but you should leave out number

char S[]= "hello\n";

will have the trailing 0 character and the array sized as needed.

With number too small you could accidentally cut off the 0 character.