title: How to find duplicates of particular column in data table in C# and return the duplicate's row number as output
body: <p>I Have a Datatable as below below image and i need to find the duplicates of only three columns(startdate,stopdate,Name), If duplicates found i need the output as row number of corresponding duplicate rows ( In this case, output should be 2,4,5) Row 2 and 4 are duplicates of Row 1 and Row 5 is the duplicate of Row 3)</p>
  
  <pre class="lang-none prettyprint-override"><code>+------+-----------+-----------+------+-------+-------+
  | S.no | StartDate | StopDate  | Name | Test1 | Test2 |
  +------+-----------+-----------+------+-------+-------+
  |    1 | 16-Dec-19 | 17-Dec-19 | Abc  |     1 |     2 |
  |    2 | 16-Dec-19 | 17-Dec-19 | Abc  |     2 |     2 |
  |    3 | 16-Dec-19 | 17-Dec-19 | def  |     3 |     2 |
  |    4 | 16-Dec-19 | 17-Dec-19 | Abc  |     4 |     2 |
  |    5 | 16-Dec-19 | 17-Dec-19 | def  |     5 |     2 |
  +------+-----------+-----------+------+-------+-------+
  </code></pre>
  
  <p>I am new to Linq Concept, If this scenario is possible in Linq, Kindly help me on this.</p>