<rule version="1">

    <pattern> if \( ([!] )*?(strlen) \( \w+? \) ([>] [0] )*?\) { </pattern>

    <message>

        <id>StrlenEmptyString</id>

        <severity>performance</severity>

        <summary>Using strlen() to check if a string is empty is not efficient.</summary>

    </message>

</rule>