Excel instance won't unload from memory

[Scott B]

I've read another post where it says to make sure you don't use unqualified
references like ActiveWorkbooks, and to make sure you set all your references
to null when Quitting Excel. I wrote a very simple C# app (below) where I am
doing these things, but the EXCEL instance can still be seen under Processes
until I close the Windows App.
In my real app, the user can be running a function a number of times, and
each one launches it's own Excel instance, so we end up with a bunch of these
in memory until the main app is closed.
We have an old VB6 app using the Excel 5 library, and it doesn't have this
problem.
Any other pointers?

-----
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace TestWriteExcel2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
Excel.Application oExcel = new Excel.Application();
oExcel.Visible = true;

try
{
Excel.Workbook obWb =
oExcel.Workbooks.Open("c:\\temp\\testWrite.xls",

System.Type.Missing,
false,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
false,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing);


Excel.Worksheet wks = (Excel.Worksheet)obWb.Worksheets[1];
Excel.Range rng = wks.get_Range("C12", System.Type.Missing);
rng.Value2 = this.textBox1.Text;
rng = null;
wks = null;
//obWb.Save();
obWb.Close(true, System.Type.Missing, System.Type.Missing);
obWb = null;
oExcel.Quit();
oExcel = null;
}
catch (Exception ex)
{

MessageBox.Show("Error opening Excel file.\n" + ex.Message);

}
}
}
}

 

[zz]

i do not no about c#, but in vba to terminate the excel entitie you need to
do "Application.Terminate" and set the oExcel object explicitally to
"nothing"

 

[Tom Ogilvy]

I don't know anything about .NET, but note that at the end of this sample,
they do garbage collection:

http://support.microsoft.com/kb/303872/en-us

Which corresponds to what I recall is a necessary step.

 

[Scott B]

Ho ho! That seemed to do it, at least in my simple test app. Now let's see
if I can apply it to my main app. Thanks.

The answer to to add GC.Collec();
--
Scott B

I don't know anything about .NET, but note that at the end of this sample,
they do garbage collection:

http://support.microsoft.com/kb/303872/en-us

Which corresponds to what I recall is a necessary step.

--
Regards,
Tom Ogilvy

I've read another post where it says to make sure you don't use unqualified
references like ActiveWorkbooks, and to make sure you set all your references
to null when Quitting Excel. I wrote a very simple C# app (below) where I am
doing these things, but the EXCEL instance can still be seen under Processes
until I close the Windows App.
In my real app, the user can be running a function a number of times, and
each one launches it's own Excel instance, so we end up with a bunch of these
in memory until the main app is closed.
We have an old VB6 app using the Excel 5 library, and it doesn't have this
problem.
Any other pointers?

-----
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace TestWriteExcel2
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
Excel.Application oExcel = new Excel.Application();
oExcel.Visible = true;

try
{
Excel.Workbook obWb =
oExcel.Workbooks.Open("c:\\temp\\testWrite.xls",

System.Type.Missing,
false,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
false,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing,
System.Type.Missing);


Excel.Worksheet wks = (Excel.Worksheet)obWb.Worksheets[1];
Excel.Range rng = wks.get_Range("C12", System.Type.Missing);
rng.Value2 = this.textBox1.Text;
rng = null;
wks = null;
//obWb.Save();
obWb.Close(true, System.Type.Missing, System.Type.Missing);
obWb = null;
oExcel.Quit();
oExcel = null;
}
catch (Exception ex)
{

MessageBox.Show("Error opening Excel file.\n" + ex.Message);

}
}
}
}

 

[Editor]

end your try / catch block with finally...

finally {
oExcel.Quit();
}