title: Search for multiple strings in a text file in c#
body: <p>Want to search a string in a file, once found, I would like to go previous and search for a different string and finally get the trailing characters of the string.</p>
  
  <p>Let's say my text in the file goes like </p>
  
  <p>line 1 ------------ sample text counterparty="ABCD" detailsprogrammed... so on</p>
  
  <p>line 2 ------------ this is line two product="12345" and continues</p>
  
  <p>I want to first search for 12345 which is unique. Once found I want to go to the previous line and search for first occurance of counterparty and once found I would like to capture the string ABCD</p>