title: Regex function to check the presence of any letter on the string or only number or symbols
body: <p>I'm a little confused about the usage of regular expression in all the entry string.</p>
  <p>I need to understand if a given string contain any number or symbols, or viceversa don't contain any letters:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>good</th>
  <th>no good</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>!</td>
  <td></td>
  </tr>
  <tr>
  <td>- 1 -</td>
  <td></td>
  </tr>
  <tr>
  <td>=&gt;</td>
  <td></td>
  </tr>
  <tr>
  <td></td>
  <td>foo</td>
  </tr>
  <tr>
  <td></td>
  <td>foo bar</td>
  </tr>
  <tr>
  <td>{</td>
  <td></td>
  </tr>
  <tr>
  <td></td>
  <td>I have 3 bananas</td>
  </tr>
  <tr>
  <td>123 456</td>
  <td></td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>So I need something like that <code>/[^A-Za-z]/</code> but in the strign I have <strong>3</strong> bananas the <code>preg_math_full</code> is fired, how can I use the regex pattern in all the string??</p>