title: Matching string format
body: <p>How is it possible to perform a matching of string, just like <code>regex</code>?</p>
  
  <p>For example i have an array of strings, I want to match if these string is in the format of <code>"abc def xxx"</code>, which <code>xxx</code> is number like <code>1</code>, <code>11</code>, <code>12</code>, <code>100</code>, <code>111</code>, etc.</p>
  
  <p>How can I achieve this?</p>