title: Check if string contains two word or special character with underscore between in PHP
body: <p>I need to check if the string contains an underscore in two words and also can be special characters:</p>
  <p>What I'm doing is:</p>
  <pre><code>preg_match('/^[a-z]+_[a-z]+$/i', $value)
  </code></pre>
  <p>Case worked:</p>
  <pre><code>mytext_second
  </code></pre>
  <p>Case not worked:</p>
  <pre><code>sometext_%
  </code></pre>
  <p>I was following this question but didn't work for me:
  <a href="https://stackoverflow.com/questions/6821679/check-if-string-contains-an-underscore-in-php">Check if the string contains an underscore in PHP</a></p>
  <p>Can anyone help me out?</p>
  <p>Thanks!</p>