Write elegant and concise code theory guidance collection

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• 3. Constantly refactor your code

1. Do not use ", use string. Empty

     string name = string.Empty;

2.Good at merging if

   public bool Equals(CommentData obj) {
      if (!CommentId.Equals(obj.CommentId)) return false;
      if (!Comment.Equals(obj.Comment)) return false;
      if (!CommentorId.Equals(obj.CommentorId)) return false;
      return true;
    }

--------- >>>

Public bool Equals (CommentData obj ){
Return CommentId = obj. CommentId &&
Comment. Equals (obj. Comment )&&
CommentorId = obj. CommentorId;
}

3. Constantly refactor your code

4. Simplify code with Linq

    foreach (CommentData data in Comments)            {                if (data.CommentId.HasValue)                    throw new ArgumentNullException("Create is only for saving new data.  Call save for existing data.", "data");            }

--------------->>>

 if (Comments.Any(data => data.CommentId.HasValue))            {                throw new ArgumentNullException("Create is only for saving new data.  Call save for existing data.", "data");            }
5. Use? : And ??
string name = value;   if (value == null){name = string.Empty;}
------------>>>
string name = (value != null) ? value : string.Empty;
Or: string name = value ?? String. Empty;
6. Use
if (employee is SalariedEmployee){    var salEmp = (SalariedEmployee)employee;    pay = salEmp.WeeklySalary;    // ...}
----------------------------------- >>>
var salEmployee = employee as SalariedEmployee;if (salEmployee != null){   pay = salEmployee.WeeklySalary;    // ...}
7. Use using to remove dispose ()
public IEnumerable<Order> GetOrders(){    SqlConnection con = null;    SqlCommand cmd = null;    SqlDataReader rs = null;    var orders = new List<Order>();    try    {        con = new SqlConnection("some connection string");        cmd = new SqlCommand("select * from orders", con);        rs = cmd.ExecuteReader();        while (rs.Read())        {            // ...        }    }    finally    {        rs.Dispose();        cmd.Dispose();        con.Dispose();    }    return orders;}
------------------------------- >>>
public IEnumerable<Order> GetOrders(){    var orders = new List<Order>();    using (var con = new SqlConnection("some connection string"))    {        using (var cmd = new SqlCommand("select * from orders", con))        {            using (var rs = cmd.ExecuteReader())            {                while (rs.Read())                {                    // ...                }            }        }    }     return orders;} 
Simplified again:
 public IEnumerable<Order> GetOrders(){    var orders = new List<Order>();     using (var con = new SqlConnection("some connection string"))    using (var cmd = new SqlCommand("select * from orders", con))    using (var rs = cmd.ExecuteReader())    {        while (rs.Read())        {           // ...        }    }     return orders;}