String.Join possible to join only 1 specific character?-CodePudding

List<string> names = new List<string>() { "John", "Anna", "Monica" };
var result = String.Join("", names.ToArray());

I would like to Join only 1 specific character from each string. Let's say, the 3rd one. Without loop if possible.

// result = "hnn"

CodePudding user response：

To Add to the Linq answers, the simplest one would likely be:

var result = String.Join("", names.Select(x => x[2]).ToArray());

Select simply maps that function over each element.
You can also extract that to a function easily:

public static string TakeNthCharacter(List<string> names, int n) {
    return String.Join("", names.Select(x => x[n]).ToArray());
}

CodePudding user response：

You can do this with LINQ:

List<string> names = new List<string>() { "John", "Anna", "Monica" };
var result = String.Join
    (
        "",
        from x in names
        select x[2]
    );

CodePudding user response：

Hello probably you want something like this:

List<string> names = new List<string>() { "John", "Anna", "Monica" };
const int specificCharacter = 2;

    var result = names.Where(name => specificCharacter < name.Length)
                      .Aggregate(string.Empty, (current, name) => current   name[specificCharacter]);

where is for you do not get a System.IndexOutOfRangeException And Aggregate to "join" the string. Here is the link with more information about it. https://docs.microsoft.com/en-us/dotnet/api/system.linq.enumerable.aggregate?view=net-6.0

CodePudding user response：

All the 3 answers work well. I tried to iterate 300.000 times all 3 of them and the second method works faster (36s against 45s for the first and 49s for the third). Therefore I valid the second answer as the main answer.