DictionaryInitialization.cs

using System.Collections.Generic;

namespace Sample
{
    public class Class
    {
        public void M()
        {
            var dic1 = new Dictionary<string, string>()
            {
                // C# 3.0～
                { "foo", "bar"},
            };

            var dic2 = new Dictionary<string, string>()
            {
                // C# 6.0～
                ["foo"] = "bar",
            };

            // target typed new (C# 9.0 ～)
            Dictionary<string, string> dic3 = new()
            {
                { "foo", "bar" },
            };

            Dictionary<string, string> dic4 = new ()
            {
                ["foo"] = "bar",
            };

        }
    }
}