how to return array object from a function? (2023)

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Visual C#

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I need to pass/retrieve as string array object, but I am getting errors with my current effort:
private string[] fldNames()
{
string[] s1 = new string[5];
for (int i = 0; i <= 5; i++)
s1[i] = i.ToString();
return s1;
}
private void button3_Click(object sender, EventArgs e)
{
string[] t1 = new string[5];
t1 = fldNames; //<---errors says something about needing a delegate to do this
}
how do I pass/call fldNames and assign it to t1? Specifically, I have a class library that I am using for com (VBA). I really need to pass this string array object to VBA. The library is working OK with VBAexcept I need to add a function that passes a list of table fieldnames to a VBA var. How do I perform the above operation in C#?
thanks,
Rich P

Wednesday, August 3, 2011 7:47 PM

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What happens if you use a 1-based array?

privateArray fldNames(){ Array s1 = Array.CreateInstance(typeof(string),new[] { 5 },new[] { 1 });for(inti = 1; i <= 5; i++) s1.SetValue(i.ToString(), i);returns1;}private voidbutton3_Click(objectsender, EventArgs e){ Array t1 = fldNames();}

Marked as answer by Rich P123 Thursday, August 4, 2011 7:17 PM

Thursday, August 4, 2011 9:10 AM

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Should be:t1 = fldNames();
Notice the brackets.

Wednesday, August 3, 2011 7:51 PM

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There are actually two issues here. First, in your fldNames method, you need to initialize this to a length of 6, not 5, since your for loop uses i <= 5 (this will happen for 0,1,2,3,4,5, which is 6 items long). Try this:
private string[] fldNames(){string[] s1 =new string[6];// Construct as an array of 6 elements for(inti = 0; i <= 5; i++) s1[i] = i.ToString();returns1;}

Second, the error you're receiving is because you're putting in the name of the method, notcallingthe method. Also, since your method creates the array, you don't need to initailize it, just set it. Try this:
private voidbutton3_Click(objectsender, EventArgs e){string[] t1;// No need to initialize, since it's being set in the next linet1 = fldNames();// Add parenthesis to call the method}
Reed Copsey, Jr. - http://reedcopsey.com
If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful".
- Proposed as answer by Pantelis44999 Wednesday, August 3, 2011 8:03 PM
Wednesday, August 3, 2011 7:59 PM

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Good catch Reed, didn't notice the loop problem.

Wednesday, August 3, 2011 8:03 PM

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thank you all for your replies. Of course, the old () missing. Well, this is now working correctly in C#. Sadly, though, in VBA it is still complaining saying that something is outside the bounds of the array. Here is what I try in VBA
Dim t As Variant
Dim x1 = New myLib.myClass //<--this is the C# Library I created
Redim t(13)
t = x1.fldNames //<--- says index is outside of the array bounds. It isn't, really
I tried to iterate x1.fldNames in VBA, but I got the same error message. I can pass/retrieve data that is not in array form OK to VBA, strings, ints. I need/want to pass a stringarray object to the VBA var. Anyone have an idea how this could be done? Should I use a list maybe? an Ilist?
Rich P

Wednesday, August 3, 2011 8:42 PM

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You're not showing all of your code, but the problem may be due to the differences in how .NET handles arrays from VBA. In VBA, arrays start at 1, not 0.
The code you have above isn't actually reading from the array, so it's difficult to know what the problem would be from seeing just that VBA snippet...
Reed Copsey, Jr. - http://reedcopsey.com
If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful".

Wednesday, August 3, 2011 9:35 PM

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We need more info to fully assist you. I am beginning to suspect that your question is outside of therealm of experienceof most participants on this forum.
CallingVisual Basic for Applications Code from Visual Basic .NET
Rudy =8^D
Mark the best replies as answers. "Fooling computers since 1971."
http://thesharpercoder.blogspot.com/

Wednesday, August 3, 2011 10:07 PM

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Well, I came up with one hack where I concatenate the table fieldnames into one string var separated by commasin the class library, and I pass this string to VBA. Then I parse the string out in VBA with the Split function. This is sort of working, but kinda hacky. Below is the source code for the VBA and for my com Class Library.
Sub VBAcode()
Dim x1 As New Database_COMObject.DBCOM_Class
Dim v As Variant, w As Variant, s1 As String, s2() As String
Dim iCols As Integer, i As Integer
v = x1.ExecuteSelectCommand("Select * From Orders Where CustomerID = 'VINET'")
If v = True Then
iCols = x1.GetColumnCnt
Debug.Print iCols
iCols = iCols - 1
s1 = x1.fldNames'--thefldNames hack function below
s2 = Split(s1, ",")
For i = 0 To UBound(s2)
Debug.Print s2(i)
Next
End If
End Sub
//--C# source code sample from internet for com class library
using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Data.SqlClient;
using System.Windows.Forms;
namespace Database_COMObject
{
[Guid("694C1820-04B6-4988-928F-FD858B95C880")]
public interface DBCOM_Interface
{
[DispId(1)]
void Init(string userid , string password);
[DispId(2)]
bool ExecuteSelectCommand(string selCommand);
[DispId(3)]
bool NextRow();
[DispId(4)]
void ExecuteNonSelectCommand(string insCommand);
[DispId(5)]
string GetColumnData(int pos);
[DispId(6)]
int GetColumnCnt();
[DispId(7)]
string fldNames();
}
// // Events interface Database_COMObjectEvents
[Guid("47C976E0-C208-4740-AC42-41212D3C34F0"),
InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
public interface DBCOM_Events
{
}

[Guid("9E5E5FB2-219D-4ee7-AB27-E4DBED8E123E"),
ClassInterface(ClassInterfaceType.None),
ComSourceInterfaces(typeof(DBCOM_Events))]
public class DBCOM_Class : DBCOM_Interface
{
private SqlConnection myConnection = null ;
SqlDataReader myReader = null ;
public DBCOM_Class()
{
}
public void Init(string userid , string password)
{
try
{
//string myConnectString = "user id="+userid+";password="+password+
// ";Database=NorthWind;Server=COMP10\\SQL2008R2;Connect Timeout=30";
//string myConnectString = "Data Source=COMP10\\SQL2008R2;Initial Catalog=NorthWind;Integrated Security=True;Connect Timeout=30";
//myConnection = new SqlConnection(myConnectString);
//myConnection.Open();
//MessageBox.Show("CONNECTED");
}
catch(Exception e)
{
MessageBox.Show(e.Message);
}
}
public bool ExecuteSelectCommand(string selCommand)
{
if ( myReader != null )
myReader.Close() ;
string myConnectString = "Data Source=COMP10\\SQL2008R2;Initial Catalog=NorthWind;Integrated Security=True;Connect Timeout=30";
myConnection = new SqlConnection(myConnectString);
myConnection.Open();
SqlCommand myCommand = new SqlCommand(selCommand);
myCommand.Connection = myConnection;
myCommand.ExecuteNonQuery();
myReader = myCommand.ExecuteReader();
return true ;
}

public bool NextRow()
{
if ( ! myReader.Read() )
{
myReader.Close();
return false ;
}
return true ;
}
public string GetColumnData(int pos)
{
Object obj = myReader.GetValue(pos);
if ( obj == null ) return "" ;
return obj.ToString() ;
}
public int GetColumnCnt()
{
return myReader.FieldCount;
}
public string fldNames()
{ //--mystring array hack
int i = myReader.FieldCount - 1;
string flds = myReader.GetName(0);
for (int j = 1; j <= i; j++)
flds += "," + myReader.GetName(j);
return flds;
}
public void ExecuteNonSelectCommand(string insCommand)
{
SqlCommand myCommand = new SqlCommand(insCommand , myConnection);
int retRows = myCommand.ExecuteNonQuery();
}
}
}
Rich P

Wednesday, August 3, 2011 10:12 PM

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What happens if you remove :Redim t(13)
It looks to me like you're passing an 7 element array to an array that's sized for 13. Not sure how VBA would handle that.

Wednesday, August 3, 2011 10:22 PM

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I have tried all sorts of iterations of an array object in VBA to receive the array object from the C# com Library -- to no avail. The only thing that is working right now is my string concatenate hack. Eventually, I would like to pass the whole (.Net) table to (Excel) VBA - same as com ADO where you can say Sheet1.Range("A1").CopyFromRecordset RS where RS is an ADODB recordset object. I'm trying to encapsulate as much functionality in my com Lib file as possible to reduce the amount of VBA coding for this project. Some things are easier to perform in C#.
Rich P

Wednesday, August 3, 2011 10:38 PM

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What happens if you use a 1-based array?

privateArray fldNames(){ Array s1 = Array.CreateInstance(typeof(string),new[] { 5 },new[] { 1 });for(inti = 1; i <= 5; i++) s1.SetValue(i.ToString(), i);returns1;}private voidbutton3_Click(objectsender, EventArgs e){ Array t1 = fldNames();}

Marked as answer by Rich P123 Thursday, August 4, 2011 7:17 PM

Thursday, August 4, 2011 9:10 AM

Quote

What happens if you use a 1-based array?

privateArray fldNames()

{ Array s1 = Array.CreateInstance(typeof(string),new[] { 5 },new[] { 1 });

for(inti = 1; i <= 5; i++)

s1.SetValue(i.ToString(), i);

returns1; }

 private voidbutton3_Click(objectsender, EventArgs e)

Array t1 = fldNames();

thanks. How do I write/extract the contents of t1 to the console? I tried a for loop --- Console.WriteLine(t1[i]); --- not working.

Rich P

Thursday, August 4, 2011 3:36 PM

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Console.WriteLine(t1.GetValue(i));

Thursday, August 4, 2011 4:26 PM

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Thanks. I tried the Array fldNames idea. I named it fldNames2. At least now in VBA the variant t is taking x1.fldNames2. But t is getting only a System.Object[] value from x1.fldNames2. Now I have to find out if there is a way I can tap into System.Object[] from VBA.
Rich P

Thursday, August 4, 2011 5:18 PM

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Yay! I did it! Here's the (Excel)VBA code I used -- and thanks for the idea of using Array fldNames instead of string[] fldNames. That did the trick!
Sub slsl()
Dim x1 As New Database_COMObject.DBCOM_Class
Dim icol As Integer, i As Integer, j As Integer
Dim v As Variant, w As Variant, t As Variant, u As Variant, s As Variant

v = x1.ExecuteSelectCommand("Select * From Orders Where CustomerID = 'VINET'")
If v = True Then
w = x1.NextRow
If w = True Then
i = x1.GetColumnCnt
Debug.Print i
t = Array(x1.fldNames2)
For Each u In t
Debug.Print u
For Each s In u
Debug.Print "*" & s & "*"
Next
Next
End If
End If
End Sub
Note: it doesn't matter if it is 1 based or 0 based array. I used a 0 based array.
Rich P

Thursday, August 4, 2011 5:25 PM

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how to return array object from a function? (2023)

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