if List contains is null

Question

 

Hi all,

If I want to say history list was null matrix [][] be 0, How could be written?

the code blew gives an error.

List <List<string> > history = new List <List<string>>()  ;

 int [][] matrix= new int[5][];

if (history[y].Contains("192.168.2.160", StringComparer.OrdinalIgnoreCase))

                        matrix[x+4][y] = 1;

else if (history[y].Contains==null)

                        matrix[x][y] = 0;

thanks