• When you paste the sample code from the Example section of the article to a Visual Basic .NET application, and then you try to compile the file, you receive the following error message:
  Name 'DTE' is not declared.
• When you try to assign the return value of the EnvDTE.Documents.Item method to an AddIn type variable, you receive the following error message:
  An unhandled exception of type 'System.InvalidCastException' occurred in ApplicationName.exe
  Additional information: Specified cast is not valid.
• When you pass an Object parameter to the EnvDTE.Documents.Item method, you receive the following error message:
  An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in ApplicationName.exe
  Additional information: Type mismatch.

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• You receive the "Name 'DTE' is not declared" error message because the variable named DTE is not declared in the sample code that is provided in the MSDN article.
• You receive the InvalidCastException error message because the MSDN article states that the return value for the EnvDTE.Documents.Item method is an AddIn type. However, the EnvDTE.Documents.Item method returns a Document type object. Therefore, when you try to assign a Document type object to an AddIn type variable, you receive the error message.
• You receive the Type mismatch error message when you try to pass a parameter that is not an Integer or a String to the EnvDTE.Documents.Item method. The EnvDTE.Documents.Item method is used to gain access to the elements of the EnvDTE.Documents collection. The EnvDTE.Documents.Item method can accept only two types of parameters:
  • Integer - for the index value of the documents in the EnvDTE.Documents collection
  • String - for the key of the documents in the EnvDTE.Documents collection

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• To use the variable named DTE, follow these steps:
  1. In Solution Explorer, right-click Your Project Name, and then click Add References.
  2. In the Add Reference dialog box, double-click envdte, and then click OK to add a reference to the EnvDTE namespace to the project.
  3. Add the following statement to the top of your Visual Studio .NET file:
     
     Visual Basic .NET Sample Code

     Imports EnvDTE

     Visual C# .NET Sample Code

     using EnvDTE;

  4. Add the following statements to the beginning of the ItemExample1 method:
     Visual Basic .NET Sample Code

     Dim DTE As EnvDTE.DTE
     DTE = System.Runtime.InteropServices.Marshal.GetActiveObject("ProgID")

     Visual C# .NET Sample Code

     EnvDTE.DTE DTE;
     DTE = (EnvDTE.DTE)System.Runtime.InteropServices.Marshal.GetActiveObject("ProgID");

     Note Replace ProgID with the ProgID of your EnvDTE object.
• To resolve the InvalidCastException error, instead of assigning the return value of the EnvDTE.Documents.Item method to an AddIn type variable, assign the return value to a Document type variable.
• To resolve the "Type mismatch" error, only pass a parameter that is an Integer or a String to the EnvDTE.Documents.Item method.

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Steps to Reproduce the Behavior

1. Start Visual Studio .NET. Use Visual Basic .NET or Visual C# .NET to create a new Windows Application project named ItemMethodDemo.
2. In Solution Explorer, right-click Form1, and then click View Code.
3. Add the following sample code for a method (from the MSDN article) to Form1:
   
   Visual Basic .NET Sample Code

   Sub ItemExample1()
      ' Closes all saved documents.
      Dim iDoc As Integer
      For iDoc = 1 To DTE.Documents.Count
         If DTE.Documents.Item(iDoc).Saved Then
            DTE.Documents.Item(iDoc).Close()
         End If
      Next iDoc
   End Sub
   

   Visual C# .NET Sample Code

   void ItemExample1()
   {
      //Closes all saved documents.
      int iDoc;
      for(iDoc=1;iDoc<DTE.Documents.Count;++iDoc)
      {
         if (DTE.Documents.Item(iDoc).Saved)
         {
            DTE.Documents.Item(iDoc).Close(EnvDTE.vsSaveChanges.vsSaveChangesYes);
         }
      }
   }

4. On the Build Menu, click Build Solution.

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