How to I check if string length equals zero in C#?

I have if statement if C# and I want to add a condition to check if string length equals zero for xml code 

<xsl:when test="(Cancelled='True') and (string-length(RescheduledReason)=0)">Cancelled</xsl:when>

Here is what I already have but I have not checked string length for RescheduledReason =0. This is what I need help to add it to my if statement.

//HearingCancelled 
if ((objxmlNode.SelectSingleNode("Cancelled") != null) && (objxmlNode.SelectSingleNode("Cancelled").InnerText == "True"))                        
{   
    objPrepHearDoc.Hearing.Settings[i].SettingStatus = "Cancelled";                     
}