public class AutoPropertyBeforeCsharp6
{
  private string _postTitle = string.Empty;
  public AutoPropertyBeforeCsharp6()
  {
    //assign initial values
    PostID = 1;
    PostName = "Post 1";
  }
 
  public long PostID { get; set; }
 
  public string PostName { get; set; }
 
  public string PostTitle
  {
    get { return _postTitle; }
    protected set
    {
      _postTitle = value;
    }
  }
}

public class AutoPropertyInCsharp6
{
  public long PostID { get; } = 1;
 
  public string PostName { get; } = "Post 1";
 
  public string PostTitle { get; protected set; } = string.Empty;
}

public class PrimaryConstructorsBeforeCSharp6
{
  public PrimaryConstructorsBeforeCSharp6(long postId, string postName, string postTitle)
  {
    PostID = postId;
    PostName = postName;
    PostTitle = postTitle; 
  }
 
  public long PostID { get; set; }
  public string PostName { get; set; }
  public string PostTitle { get; set; }
}

public class PrimaryConstructorsInCSharp6(long postId, string postName, string postTitle)
{    
  public long PostID { get; } = postId;
  public string PostName { get; } = postName;
  public string PostTitle { get; } = postTitle;
}

public class DictionaryInitializerBeforeCSharp6
{
  public Dictionary<string, string> _users = new Dictionary<string, string>()
  {
    {"users", "Venkat Baggu Blog" },
    {"Features", "Whats new in C# 6" }
  };
}

public class DictionaryInitializerInCSharp6
{
  public Dictionary<string, string> _users { get; } = new Dictionary<string, string>()
  {
    ["users"] = "Venkat Baggu Blog",
    ["Features"] = "Whats new in C# 6" 
  };
}

public class DeclarationExpressionsBeforeCShapr6()
{
  public static int CheckUserExist(string userId)
  {
    //Example 1
    int id;
    if (!int.TryParse(userId, out id))
    {
      return id;
    }
    return id;
  }
 
  public static string GetUserRole(long userId)
  {
    ////Example 2
    var user = _userRepository.Users.FindById(x => x.UserID == userId);
    if (user!=null)
    {
      // work with address ...
 
      return user.City;
    }
  }
}

public class DeclarationExpressionsInCShapr6()
{
  public static int CheckUserExist(string userId)
  {
    if (!int.TryParse(userId, out var id))
    {
      return id;
    }
    return 0;
  }
 
  public static string GetUserRole(long userId)
  {
    ////Example 2
    if ((var user = _userRepository.Users.FindById(x => x.UserID == userId) != null)
    {
      // work with address ...
 
      return user.City;
    }
  }
}

TypeName.MethodName

public class StaticUsingBeforeCSharp6
{
  public void TestMethod()
  {
    Console.WriteLine("Static Using Before C# 6");
  }
}

using System.Console;
namespace newfeatureincsharp6
{
  public class StaticUsingInCSharp6
  {
    public void TestMethod()
    {
      WriteLine("Static Using Before C# 6");
    }
  }
}

try 
{     
 //Do something
}
catch (Exception)
{
 await Logger.Error("exception logging")
}

//示例 1
try
{
  //Some code
}
catch (Exception ex) if (ex.InnerException == null)
{
  //Do work
 
}
 
//Before C# 6 we write the above code as follows
 
//示例 1
try
{
  //Some code
}
catch (Exception ex) 
{
  if(ex.InnerException != null)
  {
    //Do work;
  }
}

var userRank = "No Rank";
if(UserID != null)
{
  userRank = Rank;
}
 
//or
 
var userRank = UserID != null ? Rank : "No Rank"