C#でエクセル操作

    private void button1_Click(object sender, System.EventArgs e) {
        // 必要な変数は try の外で宣言する
        Excel.Application xlApp = null;

        // COM オブジェクトの解放を保証するために try 〜 finally を使用する
        try {
            xlApp = new Excel.Application();
            xlApp.DisplayAlerts = false;
            xlApp.Visible = true;

            Excel.Workbooks xlBooks = xlApp.Workbooks;

            try {
                Excel.Workbook xlBook = xlBooks.Add(System.Reflection.Missing.Value);

                try {
                    Excel.Sheets xlSheets = xlBook.Worksheets;

                    try {
                        Excel.Worksheet xlSheet = (Excel.Worksheet)xlSheets[1];

                        try {
                            for (int i = 1; i < 4; i++) {
                                Excel.Range xlRange = xlSheet.get_Range("A" + i.ToString(), System.Reflection.Missing.Value);

                                try {
                                    xlRange.Value2 = "=POWER(" + i.ToString() + ", 2)";
                                } finally {
                                    if (xlRange != null) {
                                        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlRange);
                                    }
                                }
                            }
                        } finally {
                            if (xlSheet != null) {
                                System.Runtime.InteropServices.Marshal.ReleaseComObject(xlSheet);
                            }
                        }
                    } finally {
                        if (xlSheets != null) {
                            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlSheets);
                        }
                    }
                } finally {
                    if (xlBook != null) {
                        try {
                            //xlBook.Close(System.Reflection.Missing.Value, System.Reflection.Missing.Value, System.Reflection.Missing.Value);
                        } finally {
                            System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBook);
                        }
                    }
                }
            } finally {
                if (xlBooks != null) {
                    try {
                        //xlBooks.Close();
                    } finally {
                        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlBooks);
                    }
                }
            }
        } finally {
            if (xlApp != null) {
                try {
                    //xlApp.Quit();
                } finally {
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp);
                }
            }
        }
    }