title: how to concat (_1) in string which is comma separeted in php?
body: <p>this code is in php </p>
  
  <pre><code> $v = 1,2,3,4,5;
  </code></pre>
  
  <p>as I have to concat <code>_1</code> in above variable </p>
  
  <p>as I need this output  <code>$v = 1_1,2_1,3_1,4_1,5_1</code></p>