How to initialize a list of strings (List<string>) with many string values

How is it possible to initialize (with a C# initializer) a list of strings? I have tried with the example below but it's not working.

List<string> optionList = new List<string>
{
    "AdditionalCardPersonAddressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
}();

Just remove () at the end.

List<string> optionList = new List<string>
            { "AdditionalCardPersonAdressType", /* rest of elements */ };

List<string> mylist = new List<string>(new string[] { "element1", "element2", "element3" });

You haven't really asked a question, but the code should be

List<string> optionList = new List<string> { "string1", "string2", ..., "stringN"}; 

i.e. no trailing () after the list.

var animals = new List<string> { "bird", "dog" };
List<string> animals= new List<string> { "bird", "dog" };

Above two are the shortest ways, please see https://www.dotnetperls.com/list

Your function is just fine but isn't working because you put the () after the last }. If you move the () to the top just next to new List<string>() the error stops.

Sample below:

List<string> optionList = new List<string>()
{
    "AdditionalCardPersonAdressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
};

This is how you initialize and also you can use List.Add() in case you want to make it more dynamic.

List<string> optionList = new List<string> {"AdditionalCardPersonAdressType"};
optionList.Add("AutomaticRaiseCreditLimit");
optionList.Add("CardDeliveryTimeWeekDay");

In this way, if you are taking values in from IO, you can add it to a dynamically allocated list.

One really cool feature is that list initializer works just fine with custom classes too: you have just to implement the IEnumerable interface and have a method called Add.

So for example if you have a custom class like this:

class MyCustomCollection : System.Collections.IEnumerable
{
    List<string> _items = new List<string>();

    public void Add(string item)
    {
	    _items.Add(item);
    }

    public IEnumerator GetEnumerator()
    {
	    return _items.GetEnumerator();
    }
}

this will work:

var myTestCollection = new MyCustomCollection()
{
	"item1",
	"item2"
}

Move round brackets like this:

var optionList = new List<string>(){"AdditionalCardPersonAdressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"};

There is something else that you might be missing that hasn't been mentioned. I think it might be the problem you are having as I suspect you already tried removing the trailing () and still got an error.

First, like others have mentioned here, in your example you do need to remove the trailing ();

But, also, note that List<> is in the System.Collections.Generic namespace.

So, you need to do one of the following two options: [#1 below is probably the more preferred option]

(1) Include the use of the namespace at the top of your code with: using System.Collections.Generic;

or

(2) Put the fully qualified path to List in your declaration.

System.Collections.Generic.List optList=new System.Collections.Generic.List { "AdditionalCardPersonAddressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay" };

Hope that helps.

The error message you receive when you implement List correctly but don't include the System.Collections.Generic namespace is misleading and not helpful:

"Compiler Error CS0308: The non-generic type List cannot be used with type arguments."

PS - It gives this unhelpful error because if you don't specify that you intend to use System.Collections.Generic.List the compiler assumes you are trying to use System.Windows.Documents.List.

The right way to initialize along with declaration is :

List<string> optionList = new List<string>()
{
    "AdditionalCardPersonAdressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
};

I have seen the content tag C#, but if someone could use Java (the same search terms lead here):

List<String> mylist = Arrays.asList(new String[] {"element1", "element2", "element3" }.clone());

If you are using C# 9.0 and up you can use the new feature target-typed new expressions Link

Example:

List<string> stringList = new(){"item1","item2", "item3"} ;

This is how you would do it.

List <string> list1 = new List <string>();

Do Not Forget to add

using System.Collections.Generic;