title: C# Proper Way to Close Multiple Excel Objects With Excel Process Destroyed
body: <p>I have a C# console program. When it runs, it instantiates some Excel objects such as: (openExcelO). </p>
  
  <p>When the program is done running, I have a method to close down Excel (closeExcel) and that is supposed to properly clean up the Excel process. In task manager I can see the remnants of Excel that remain. The shut down routines were cobbled together from internet examples:</p>
  
  <pre><code>    private void openExcelO (string dir) {
  
          try {
              xlApp = new Excel.Application();
              xlWorkBook = xlApp.Workbooks.Open(dir + "PortfolioOptimization5.xlsm",
                  0, false, 5, "", "", true, 
                  Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, 
                  "\t", false, false, 0, true, 1, 0);
              xlMarkowitz = (Excel.Worksheet)xlWorkBook.Sheets["Markowitz"];
              xlWeights = (Excel.Worksheet)xlWorkBook.Sheets["Weights"];
  
          } catch (Exception ex) {
              ReportError("PortfolioOptimization", "openExcel", ex.ToString());
          }
  
      }
  
  
      private void closeExcel () {
          object misValue = System.Reflection.Missing.Value;
          try {
  
              if (xlWeights != null) releaseObject(xlWeights);
              if (xlMarkowitz != null) releaseObject(xlMarkowitz);
  
              xlWorkBook.Close(false, misValue, misValue);
              if (xlApp != null) xlApp.Quit();
  
              if (xlWorkBook != null) releaseObject(xlWorkBook);
              if (xlApp != null) releaseObject(xlApp);
  
          } catch (Exception ex) {
              ReportError("PortfolioOptimization", "closeExcel", ex.ToString());
          }
      }
  
  
      private void releaseObject (object obj) {
          try {
              System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
              obj = null;
          } catch (Exception ex) {
              obj = null;
              ReportError("PortfolioOptimization", "releaseObject", "Unable to release object " + ex.ToString());
          } finally {
              GC.Collect();
          }
      }
  </code></pre>
  
  <p>How can I change the shutdown routine to properly shut down and clean up the Excel objects so there are no lingering Excel processes in the Task Manager?</p>
  
  <p>Thanks!</p>