title: Extract substring from one index to another index
body: <p>VB.NET has a <code>Substring</code> method that takes the starting index and the length of the substring as parameters. Is it possible to extract a substring from one index to another (instead of using length)? </p>
  
  <p>For example, if I had a string <code>"1 + 1 = 2"</code>, and I wanted to extract everything between the <code>+</code> and the <code>=</code> I'd like to be able to do something like: </p>
  
  <pre><code>string.Substring(string.IndexOf("+") + 1, string.IndexOf("=") - 1)
  </code></pre>
  
  <p>The reason I don't want to use length is because I'm unsure how many digits the number will be between the <code>+</code> and the <code>=</code>. </p>
  
  <p>Is Regex my only option or am I missing something simple?</p>