How to make inside of the spiral pattern

See more:

C

I´m trying to make a spiral pattern (just starting with C programming) and I don´t know hot to make inside of the spiral. I´ve tried to do it manually to n=15(like spiral 15x15) but it got messy when n=12 and more.

What I have tried:

For now I have the "cover" of the spiral:

<pre>int main()
{
		int N;
		scanf("%d", &N);
		for(int i = 0 ; i < N ; i++){
			for(int j = 0 ; j < N ; j++){
				if(i == 0 || i == N-1 || j == 0 || j == N-1) {
					if (i == 1 && j == 0) {
						printf(".");
					}else {
						printf("#");
					}
				}else {
					printf(".");
				}
			}
			printf("\n");
		}
	}

For example:

For n=5 it looks like this

#####
....#
#...#
#...#
#####

For n=10 like this:

##########
.........#
#........#
#........#
#........#
#........#
#........#
#........#
#........#
##########

What I want is a spiral like this:

For example for n=7 it is:

#######
......#
#####.#
#...#.#
#.###.#
#.....#
#######