To find neighbours

Lets suppose that we have an array which looks like this:


#(#(O O O O)
  #(O O X O)
  #(O O O O))

How would I go about to find the neighbours of 'X
without using loads of if-else ?

>>1
Use bit masks

>>17
One also could also run a bit window against data and count matchin bits (modern CPU support bitcount function). A pretty general technique, you can use to pattern match any data.