Finding neighbours in a two-dimensional array

Question

Is there an easy way of finding the neighbours (that is, the eight elements around an element) of an element in a two-dimensional array? Short of just subtracting and adding

Answer 1

Rows and Cols are total number of rows and cols

Define a CellIndex struct or class. Or you can just return the actual values instead of the indexes.

public List GetNeighbors(int rowIndex, int colIndex)
{
var rowIndexes = (new int[] { rowIndex - 1, rowIndex, rowIndex + 1 }).Where(n => n >= 0 && n < Rows);

var colIndexes = (new int[] { colIndex - 1, colIndex, colIndex + 1 }).Where(n => n >= 0 && n < Cols);

return (from row in rowIndexes from col in colIndexes where row != rowIndex || col != colIndex select new CellIndex { Row = row, Col = col }).ToList();
}