title: How to match regex with same format but different in terms of character set?
body: <p>Suppose i have a string and i want to match only the part where value is empty and not the part where value is present?
  for ex : &amp;lang=&amp;val=1233 
  I need only &amp;lang and not &amp;val as it has an actual value?
  I have this </p>
  
  <p><code>&amp;(.+)=(?!\s\S)</code>
   regex which matches &amp;lang=&amp;val= in the string.
  Can anyone help me out</p>