title: Convert String variable to long
body: <p>While i was writing today i've met a very stupid problem:
  On one place i must give a long value like 0x70, 0x3BC0 or something like that.
  This values i must take from a text file.
  I am using System.IO like this:</p>
  
  <pre><code>string[] stringTakenByFile = File.ReadAllLines(@"thePathToFile.txt");
  </code></pre>
  
  <p>From here i can take the value but in string format. I mean the same value like 0x70 but not like a long or int but like a text (string). When i try to parse it or convert it from string to int/long it gives me an exception witch says: Input string was not in a correct format.
  If you could help me that would be awesome!
  Thanks!
  EDIT: I dont wanna "How to convert numbers between hexadecimal and decimal in C#?" i need from string to LONG</p>