MS Word Automation in C# - Unable to cast object of type 'System.String[*]' to type 'System.String[]'

Question

I use this code to get a String array of headings used in a MS Word 2007 document (.docx):

dynamic arr = Document.GetCrossReferenceItems(WdReferenceType.wdRe         


        

Answer 1

try

object arr_r = Document.GetCrossReferenceItems(WdReferenceType.wdRefTypeHeading);
Array arr = ((Array) (arr_r));

string myHeading = (string) arr.GetValue(1);

Answer 2

string[] is a vector - a 1-d, 0-based array. string[*], however, is a regular array that just happens to have one dimension. Basically, you are going to have to handle it as Array, and either copy the data out, or use the Array API rather than the string[] API.

This is the same as the difference between typeof(string).MakeArrayType() (the vector) and typeof(string).MakeArrayType(1) (a 1-d non-vector).

Answer 3

The problem is that you're using dynamic in a situation where it apparently wasn't intended. When the dynamic runtime sees a 1D array, it assumes a vector, and tries to index into it or enumerate it as if it were a vector. This is one of those rare cases where you have a 1D array that is not a vector, so you have to handle it as an Array:

Array arr = (Array)(object)Document.
            GetCrossReferenceItems(WdReferenceType.wdRefTypeHeading);
// works
String arr_elem = arr.GetValue(1);
// now works
IEnumerable list = (IEnumerable)arr; 
// now works
foreach (String str in arr)
{
    Console.WriteLine(str);
}