What are the outcodes that would be assigned to these points? In Cohen-Sutherland clipping, it assigns outcodes to the points on lines that are drawn to specify their orientation relative to the clipping window. 

In the diagram below, I'm confused on what outcodes that would be assigned to p1, p2, p3, p4? Can someone explain?
The diagram on the Wikipedia entry for Cohen-Sutherland Clipping explains it pretty well:

        left    central right
top     1001    1000    1010
central 0001    0000    0010
bottom  0101    0100    0110


So in your example, p1 would be left, central, so its code  would be 0001.

p2 would be central, bottom, so 0100

p3 would  be  central, central, so 0000

p4 would be central, top, so 1000