C#.NET excel automation question

Question

Hello all never worked much with C#.NET before and I have been following this example step by step: http://support.microsoft.com/default.aspx?scid=kb;EN-US;302084 I have also tried numerous other solutions found on the web. All I want to do is click a button on a c# windows form and have it spawn an excel spreadsheet (and eventually write data to it). I am running xp professional and office 2000 premium and coding with visual studio.net 2003. I follow the steps that page tells me to do precisely however on step 3(b) where it says to add Microsoft Excel Object Library on the COM tab I do not have that I have Microsoft Excel 9.0 Object Library safe to assume its the same thing? After doing everything else it says I try running it and get: Namespace '' already contains a definition for 'Excel' I have looked around for days trying to figure out what exactly I am doing wrong and have found nothing to help me. Anyone have any ideas? I can post code if it helps but as I said its EXACTLY what was listed on the link above. Any help is greatly appreciated. thanks Dave

golfingirishman · Answer

Simon Thanks for your advice its much appreciated. I have reviewed the object browser and have modified the code to look as such... still very simple: using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using Excel; using System.Reflection; namespace WindowsApplication7 { public class Form1 : System.Windows.Forms.Form { private System.Windows.Forms.Button button1; private System.ComponentModel.Container components = null; public Form1() { InitializeComponent(); } protected override void Dispose( bool disposing ) { if( disposing ) { if (components != null) { components.Dispose(); } } base.Dispose( disposing ); } #region Windows Form Designer generated code private void InitializeComponent() { this.button1 = new System.Windows.Forms.Button(); this.SuspendLayout(); this.button1.Location = new System.Drawing.Point(104 80); this.button1.Name = button1; this.button1.TabIndex = 0; this.button1.Text = button1; this.button1.Click += new System.EventHandler(this.button1_Click); this.AutoScaleBaseSize = new System.Drawing.Size(5 13); this.ClientSize = new System.Drawing.Size(292 273); this.Controls.Add(this.button1); this.Name = Form1; this.Text = Form1; this.ResumeLayout(false); } #endregion [STAThread] static void Main() { System.Windows.Forms.Application.Run(new Form1()); } private void button1_Click(object sender System.EventArgs e) { Excel.Application oXL; Excel._Workbook oWB; Excel._Worksheet oSheet; oXL = new Excel.Application(); oXL.Visible = true; oXL.UserControl = true; } } } in the above example the using Excel; line seems to work just fine because I can see in the windows taskbar that Excel processes are being created by the oXL = new Excel.Application(); line. However the oXL.Visible = true; line keeps giving me the following: An unhandled exception of type 'System.InvalidCastException' occurred in WindowsApplication7.exe Additional information: QueryInterface for interface Excel._Application failed. Can you help me out with where exactly i'm casting something and why I just cant get this to work? Using intellisense I see that Visible is a valid attribute so i'm stumped once again.. I really dont know what it's trying to tell me here! thanks in advance dave

shimtanny · Answer

Hi Namespaces of the pia's (primary interop assemblies) are different from version to version. So ensure that Microsoft.Office.Interop.Excel really exists and if not the pia's are offer directly the namespace excel. VS and intellisense will help you also the objetc browser could help you to find out the correct namespaces. Simon

golfingirishman · Answer

also if it helps the error is occuring on line 7 of the example where it says... using Excel = Microsoft.Office.Interop.Excel; thanks