title: C# Replace part of a string
body: <p>How can I replace part of a string that has a potentially unknown starting index. For instance, if I had the following strings: </p>
  
  <pre><code>"&lt;sometexthere width='200'&gt;"
  "&lt;sometexthere tile='test' width='345'&gt;"
  </code></pre>
  
  <p>I would be looking to replace the width attibute value that can have an unknown value and as mentioned before an unknown start index.</p>
  
  <p>The I understand that I would somehow have to base this on the following part, which is constant, I just don't quite understand how to achieve this. </p>
  
  <pre><code>width='
  </code></pre>