title: How to check an excel workbook is already open in C# win forms
body: <p>I am opening multiple excel files in my application. Some will be automatically open when the application starts whereas some are opening at the run time.</p>
  
  <p>Now I want to get data from an excel file on a button click. But before opening it, I want to check that excel file is already open.</p>
  
  <ol>
  <li>If it is <strong>open</strong>, I want to read from it directly.</li>
  <li>if it is <strong>not open</strong>, I want to open it and read from it.</li>
  </ol>
  
  <p>But in both the cases I don't want to close the file after reading.`</p>
  
  <p>I am using this method to open excel file.</p>
  
  <pre><code>objExcel = new Excel.ApplicationClass();
  objWorkbook = objExcel.Workbooks.Open(...);`
  </code></pre>
  
  <p>Please help I am new to C#.</p>