Equivalent of C# ?

**Pirate** · Mar 14th, 2003, 12:31 PM

In VB.NET I use this

VB Code:

Public Shared Sub OpenDB()
If Not MyConnection.State = ConnectionState.Open Then
 MyConnection.Open()
Else
msgbox ("Connection already open ")
End If
End Sub

What's C# equivalent ?
Thanx

**Pirate** · Mar 14th, 2003, 12:33 PM

I stuck only in the (if not ) clause ?? I know everything else !

**hellswraith** · Mar 14th, 2003, 12:34 PM

This is off the top of my head, and very well have some problems with it...

Code:

public static void OpenDB()
{
   if(!(MyConnection.State == ConnectionState.Open))
   {
      MyConnection.Open();
   }
   else
   {
      MessageBox.Show("Connection already open");
   }
}

**Pirate** · Mar 14th, 2003, 12:36 PM

Thanx for this fast response !

**Pirate** · Mar 14th, 2003, 03:01 PM

again what's C# equivalent for (nothing) keyword . I couldn't figure it out !

VB Code:

Dim Tables As DataTable = MyConnection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, New Object() {Nothing, Nothing, Nothing, "TABLE"})

thanx

**hellswraith** · Mar 14th, 2003, 03:01 PM

No problem, it worked for what you wanted?

**Pirate** · Mar 14th, 2003, 03:11 PM

never mind , it's null . Next time I should have a look at C# Keywords .

**Pirate** · Mar 14th, 2003, 03:19 PM

Originally posted by hellswraith
No problem, it worked for what you wanted?

yeah worked fine .

btw , how can import class1 data members ?
in vb.net we do this :

import Class1.Myclass.Myfunction

thanx !

**Cagez** · Mar 14th, 2003, 03:34 PM

I'm just a newbie but I thought it was the using keyword

Code:

using Namespace.Class blah blah blah

Mabe that'll help a little bit

**Pirate** · Mar 14th, 2003, 03:38 PM

Originally posted by Cagez
I'm just a newbie but I thought it was the using keyword

Code:

using Namespace.Class blah blah blah

Mabe that'll help a little bit

Nope !

**hellswraith** · Mar 14th, 2003, 04:01 PM

Not sure exactly what you need. I would have said the using statement myself, but it seems like you are doing something different. Give some more VB code that shows how your using it so I can understand better what your asking.

**Pirate** · Mar 14th, 2003, 04:11 PM

Originally posted by Pirate
yeah worked fine . btw , how can import class1 data members ?
in vb.net we do this :

import Class1.Myclass.Myfunction
thanx !

I thought the post explain itself

How can I shorten a function path . for example

I can do this , so I don't have to continue typing the whole path to IO members

Import System.IO.

Path.method (instead of doing this System.IO.Path.method

Clear ??

**SimonVega** · Mar 14th, 2003, 04:34 PM

You can use the 'using' directive:

Code:

using System.IO;

**Pirate** · Mar 14th, 2003, 04:42 PM

Originally posted by SimonVega
You can use the 'using' directive:

Code:

using System.IO;

IO class was only example . I need to import (using in C#) classes and voids from Class1 . What should I do ?

I've been trying this but with no luck

I want to get this :
using Class1.Mydatabase.OpenDB

come on guys this is easy ! This is my first day with C# ! It was the worst .

**SimonVega** · Mar 14th, 2003, 05:11 PM

I think I know where your stuck. When using static members, you have to reference the member using the class name:

Code:

   public class HelloWorld
   {
        public static void DisplayMsg()
        {
             Console.Write("Hello World");
        }  

        static void Main()
        {
            //Note: You can not use an object reference
            HelloWorld.DisplayMsg();
        }   
    }

Welcome to the dark side!

**Pirate** · Mar 15th, 2003, 01:46 AM

I should explained that well ! I do this everyday in VB.NET . I don't know if I can do this in C# ??
I have a namespace called "Mydatabase" and one big class called "DBClass" and many functions under "DBClass" class .
all of them are static (shared) . I call them in form1 like so :

Code:

Mydatabase.DBClass.OpenDB();

how can I shorten the its name to be called like this :

Code:

OpenDB();

I believe it can be done by using Keyword but I couldn't find it there ?

**Cagez** · Mar 15th, 2003, 02:35 AM

Sorry if I'm becoming repetitive, but have you tried this?

Code:

using Mydatabase.DBClass;

It should go at the very top of your form code, where the other using statements are.

**SimonVega** · Mar 15th, 2003, 02:43 AM

I already covered this a few threads up. There is no such thing as global functions in C#. To reference a static member of a class, you have to use the class name following by the dot notation...

It should go at the very top of your form code, where the other using statements are.

You can only apply the using namespace directive against namespaces, not classes.

**Pirate** · Mar 15th, 2003, 02:51 AM

Cagez , yes I've tried that but it seem SimonVega is right . It's only applied to namespaces ! but how come this happens :

Code:

using System.Windows.Forms.Design

System is namespace but others are classes ???
C# is confusing to me at least . VB.NET can do such stuff easily !

**Pirate** · Mar 15th, 2003, 02:56 AM

Class1.cs(73): Type and identifier are both required in a foreach statement

what's wrong with this code ??

Code:

public static void LoadTables (System.Windows.Forms.TreeView TreView)
			{
				OpenDB.OpenDB1();
				DataTable Tables =MyConnection().GetOleDbSchemaTable(OleDbSchemaGuid.Tables,new object[] {null,null,null,"TABLE"});
				CloseDB.CloseDB1 ();

				if (Tables.Rows.Count > 0)
				{
					TreView.BeginUpdate ();
				}
					DataRow dr;
				foreach (dr in Tables.Rows)
				{
					TreView.Nodes.Add (new  TreeNode(dr("TABLE_NAME")));
				}
				Tables = null;
			}

it shows blue line on "in" word . Why ?

**SimonVega** · Mar 15th, 2003, 03:14 AM

You have to specify the type in the foreach construct:

Code:

foreach(DataRow r in t.Rows)
    Console.WriteLine(r[0]);

**SimonVega** · Mar 15th, 2003, 03:16 AM

Code:

using System.Windows.Forms.Design

System is namespace but others are classes ???

'System.Windows.Forms.Design' is a nested namespace.

**Pirate** · Mar 15th, 2003, 03:38 AM

This is VB version

VB Code:

'TreeView
            Public Overloads Shared Sub LoadTables(ByVal TreView As TreeView)
                'see if connection is already open
                OpenDB.OpenDB()
                Dim Tables As DataTable = MyConnection.GetOleDbSchemaTable(OleDb.OleDbSchemaGuid.Tables, _
                New Object() {Nothing, Nothing, Nothing, "TABLE"})
 
                CloseDB.CloseDB()
 
                '"TABLE_CATALOG" is the database name
                '"TABLE_NAME" is the table name
                If Tables.Rows.Count > 0 Then
                    TreView.BeginUpdate()
                    Dim dr As DataRow
                    For Each dr In Tables.Rows
                                                TreView.Nodes.Add(New TreeNode(dr("TABLE_NAME")))
Next
TreView.EndUpdate()
End If
Tables = Nothing
End Sub

I've tried your way SimonVega but gave me error :
Class1.cs(77): 'dr' denotes a 'variable' where a 'method' was expected
in this line

Code:

TreView.Nodes.Add (new TreeNode(dr()("TABLE_NAME")));

Thank you for trying to solve my problem !

**SimonVega** · Mar 15th, 2003, 11:20 AM

This is what you were supposed to change:

Code:

foreach (DataRow dr in Tables.Rows) {
    TreView.Nodes.Add (new  TreeNode(dr("TABLE_NAME")));
}

**Pirate** · Mar 15th, 2003, 12:14 PM

No , that didn't help ! Still getting that error !

Class1.cs(77): 'dr' denotes a 'variable' where a 'method' was expected
in this line

Code:

foreach (DataRow dr in Tables.Rows) {
    TreView.Nodes.Add (new  TreeNode(dr("TABLE_NAME")));
}

any help guys ??

**SimonVega** · Mar 15th, 2003, 01:06 PM

There is also another syntax error in your code:

Code:

foreach (DataRow dr in Tables.Rows) {
    TreView.Nodes.Add (new  TreeNode(dr["TABLE_NAME"]));
}

You need to reference the indexer using squar brackets.

**Pirate** · Mar 15th, 2003, 01:13 PM

Sorry didn't work either . I got these errors when I tried your code !

1- Class1.cs(76): The best overloaded method match for 'System.Windows.Forms.TreeNode.TreeNode(System.Windows.Forms.TreeView)' has some invalid arguments

2-Class1.cs(76): Argument '1': cannot convert from 'object' to 'System.Windows.Forms.TreeView'

. any suggestions plz ??

**SimonVega** · Mar 15th, 2003, 01:45 PM

Ok...I was merely checking your syntax, not actually running the code. I'm not at my dev box, but here is why i think it is not compiling. When you read the column data out from the data row, use the tostring() method to convert it to a string.

Code:

foreach (DataRow dr in Tables.Rows) {
    TreView.Nodes.Add (new TreeNode(dr["TABLE_NAME"].ToString()));
}

**Pirate** · Mar 15th, 2003, 01:56 PM

I got a lot of errors . I believe it's not conversion problem ! it has to do with "in" till the end . Dunno really I though that was simple .

Code:

public static void LoadTables (System.Windows.Forms.TreeView TreView)
			{
				OpenDB.OpenDB1();
				DataTable Tables =MyConnection().GetOleDbSchemaTable(OleDbSchemaGuid.Tables,new object[] {null,null,null,"TABLE"});
				CloseDB.CloseDB1 ();

				if (Tables.Rows.Count > 0)
				{
					TreView.BeginUpdate ();
				}
				DataRow dr;
				
				foreach (dr in Tables.Rows()) 
				{
					TreView.Nodes.Add (new  TreeNode(dr("TABLE_NAME")));
				}
      Tables = null;
}

I appreciate your help SimonVega .
Thank you

**SimonVega** · Mar 15th, 2003, 02:08 PM

Here is a sample I just wrote up that works and your code should somewhat resemble:

Code:

private void button1_Click(object sender, System.EventArgs e) {
    DataTable t = new DataTable();
    DataRow r = t.NewRow();
    t.Columns.Add("ID", typeof(System.Int32));
    r[0] = 10;
    t.Rows.Add(r);

    TreeNode root = treeView1.Nodes.Add("Root");
    foreach(DataRow row in t.Rows)
        root.Nodes.Add(new TreeNode(row["ID"].ToString()));	
}

**Pirate** · Mar 16th, 2003, 02:24 PM

Didn't help either ! It gives me a different error , seems simpler but I coudn't solve it though !

Class1.cs(78): 'dr' denotes a 'variable' where a 'method' was expected

Code:

foreach (DataRow dr in Tables.Rows) 
{
root = TreView.Nodes.Add("Root");	
TreView.Nodes.Add(new TreeNode(dr("TABLE_NAME")));
//nor this 
//TreView.Nodes.Add(new TreeNode(dr()("TABLE_NAME")));
}

Thanx dude !

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