title: Extract only 5-digit-number in a string
body: <p>I have an address such that <code>81000</code> is the postal code (always a 5-digit-number).</p>
  
  <pre><code>address &lt;- "F47, First Floor, PTD 106273, Persiaran Indahpura Utama, Bandar Indahpura, 81000 Kulaijaya, Johor"
  </code></pre>
  
  <p>I am trying to determine the postal code using <code>regex</code> and I have tried the following:</p>
  
  <pre><code>## postal code pattern
  postal_pattern &lt;- '\\d{5}'
  ## extract postal code
  postal_code &lt;- stringr::str_extract_all(address, postal_pattern)
  </code></pre>
  
  <p>However, I got the following output, which is partially correct:</p>
  
  <pre><code>&gt; postal_code
  [[1]]
  [1] "10627" "81000"
  </code></pre>
  
  <p>How can I only extract <code>81000</code> using <code>regex</code> or any libraries?</p>