title: Check if a String matches specific regular expression
body: <p>I am not so good with regular expressions and stuff, so I need help. I have to check if a input value matches a specific regular expression format. Here is the format I want to use, <code>25D8H15M</code>. Here the <code>D</code> means the # of days <code>H</code> means hours and <code>M</code> means minutes. I need the regular expression to check the String. Thanks</p>