Linq query string array inside List of strings

Question

Hey all I am trying to query for the string number thats in the first position inside my List:

List<string[]> idMainDescriptionIcon = new List<string[]>(){
   //              [ID]       [Main]               [Description]               "XX[d=day or n=night]"
   new string[4] { "200", "Thunderstorm",  "thunderstorm with light rain",     "11" },
   new string[4] { "201", "Thunderstorm",  "thunderstorm with rain",           "11" },
   new string[4] { "202", "Thunderstorm",  "thunderstorm with heavy rain",     "11" },
   new string[4] { "210", "Thunderstorm",  "light thunderstorm",               "11" },
   new string[4] { "211", "Thunderstorm",  "thunderstorm",                     "11" }
};

And the Linq I am using:

List<string> d = idMainDescriptionIcon[0][0]
  .Where(x => x.StartsWith("202"))
  .Select(x => x)
  .ToList();

I am getting an error on the idMainDescriptionIcon[0][0] stating:

Error CS1061 'char' does not contain a definition for 'StartsWith' and no accessible extension method 'StartsWith' accepting a first argument of type 'char' could be found (are you missing a using directive or an assembly reference?)

The D should have the values of "202", "Thunderstorm", "thunderstorm with heavy rain", "11".

And this is where I am stuck at. Not sure how to go about fixing this error?

UPDATE #1

When removing the [0][0] and replacing it with just one [0] this is the return I get:

Thanks for the reply @Jawad. I have updated my OP to show what I get when only using the one [0] instead of [0][0]. — StealthRT
– StealthRT, Commented Oct 26, 2021 at 2:13

Anu Viswan · Accepted Answer · 2021-10-26 03:49:37Z

1

The problem here is idMainDescriptionIcon[0][0], which is referring to a single string here. Iterating over it would be iterating over characters in the string, which is why you get the error 'char' does not contain a definition for 'StartsWith'

What you would need is the following

var d = idMainDescriptionIcon
  .Where(x => x[0].StartsWith("202"))
  .SelectMany(x => x)
  .ToList();

You need to query the entire idMainDescriptionIcon such that the first element of the inner array starts with "202".

Alternatively,

var d = idMainDescriptionIcon
  .FirstOrDefault(x => x[0].StartsWith("202"))
  .ToList();

Output

edited Oct 26, 2021 at 3:49

answered Oct 26, 2021 at 2:14

Anu Viswan

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5 Comments

StealthRT Over a year ago

That did the trick Anu! It works as it should now :)

Joel Coehoorn Over a year ago

You may also have been right about SelectMany(), where the op wants a collection of strings directly, though that is a slightly unusual way to request the data.

Anu Viswan Over a year ago

@JoelCoehoorn Any particular reason to prefer x[0] over First() in your Edit?

Corey Over a year ago

The combination of StartsWith() in the Where() along with SelectMany() could result in unexpected output depending on what @StealthRT is attempting. Replacing Where() with FirstOrDefault() might be better.

Anu Viswan Over a year ago

@Corey Done, Thanks for the suggestion

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