Thread: colon in the structure

what is the use of colon in the structure.

Code:

int main ()
{
	struct {
		int p:4;
		int k:4;
	}l;

	l.p=10;
	l.k=1000;

	printf("%d\n",l.p);
	printf("%d\n",l.k);
	return 0;
}

output:
-6
-8