How to search in 2D array by LINQ ?[version2]

Question

I have an 2D array like this:

string[,] ClassNames =
{
  {\"A\",\"Red\"},
  {\"B\",\"Blue\"},
  {\"C\",\"Pink\"},
  {\"D\",\"Green\"},
  {\"         


        

Answer 1

You can do use the Enumerable.Range method to generate a sequence of integers, and then use Linq to query over that.

Something like this would work:

string color = Enumerable
    .Range(0, ClassNames.GetLength(0))
    .Where(i => ClassNames[i, 0] == className)
    .Select(i => ClassNames[i, 1])
    .FirstOrDefault() ?? "Black"; 

Or in query syntax:

string color = 
    (from i in Enumerable.Range(0, ClassNames.GetLength(0))
     where ClassNames[i, 0] == className
     select ClassNames[i, 1])
    .FirstOrDefault() ?? "Black"; 

Or perhaps convert the array to a Dictionary first:

Dictionary ClassNamesDict = Enumerable
    .Range(0, ClassNames.GetLength(0))
    .ToDictionary(i => ClassNames[i, 0], i => ClassNames[i, 1]);

And then you can query it much more easily:

color = ClassNamesDict.ContainsKey(className) 
      ? ClassNamesDict[className] 
      : "Black"; 

Generating the dictionary first and then querying it will be far more efficient if you have to do a lot of queries like this.