需要帮助C＃错误：对象引用未设置为对象的实例

Question

您能否帮我解决错误消息：

  

“对象引用未设置为对象的实例。”

我通过评论和**

标记了我收到错误的区域

请参阅下文。

private static void _GenerateWord(string fname, string reportStartDate, string reportEndDate)
        { 
            var word = new Microsoft.Office.Interop.Word.Application();
            var doc = new Microsoft.Office.Interop.Word.Document();
            word.Visible = false;
            object missing = Type.Missing;

            object fileName = (@LetterTemplateLocation + LetterName);

            doc = word.Documents.Open(ref fileName);


            doc.Activate();//**Error message here "Object reference not set to an instance of an object."**

            string dateWithFormat = DateTime.Now.ToString("MMMM d, yyyy");

            //**Error message here "Object reference not set to an instance of an object."**
            foreach (Microsoft.Office.Interop.Word.Range tmpRange in doc.StoryRanges)
            {
                _FindAndReplace("<date>", dateWithFormat, tmpRange, missing);

                _FindAndReplace("<filename>", fname, tmpRange, missing);

                _FindAndReplace("<startdate>", reportStartDate, tmpRange, missing);

                _FindAndReplace("<enddate>", reportEndDate, tmpRange, missing);
            }

            if (doc != null)
            {
                doc.Close(ref missing, ref missing, ref missing);
                word.Application.Quit(ref missing, ref missing, ref missing);
            }
        }

谢谢。

Answer 1

作为一种做法，需要检查doc for null。

  

如果（doc！= null）{...}

还需要像其他人建议的那样评估有效文件。