List OrderBy Problems

List <List1Dto> listResult = new List <List1Dto> ();

ListResult. Add (new List1Dto {UserName = "user1", UserPwd = "user1", UserTitle = "user1", OrderNumber = "1 "});

ListResult. Add (new List1Dto {UserName = "user2", UserPwd = "user2", UserTitle = "user2", OrderNumber = "2 "});

ListResult. Add (new List1Dto {UserName = "user10", UserPwd = "user10", UserTitle = "user10", OrderNumber = "10 "});

ListResult. Add (new List1Dto {UserName = "user20", UserPwd = "user20", UserTitle = "user20", OrderNumber = "20 "});

List <List1Dto> list1 =ListResult. OrderBy (ao => ao. OrderNumber). ToList ();

String tmp = "";

Foreach (List1Dto item in list1)

{

Tmp + = item. UserName + "\ r \ n ";

}

Result:

User1

User10

User2

User20

Modify:

List <List1Dto> list1 =ListResult. OrderBy (ao => Convert. ToInt32 (string. IsNullOrEmpty (ao. OrderNumber )? "0": ao. OrderNumber). ToList ();