c# - How to implement System.currentTimeMillis() method in WPF? -

i'm trying create unique tranactionid using ${=system.currenttimemillis()} in wpf textbox following :

writer.writestartelement("transactionid");  writer.writestring(textbox22.text);  <textbox x:name="textbox22" horizontalalignment="left" height="23"  margin="388,392,0,0" textwrapping="wrap" text="${=system.currenttimemillis()}" verticalalignment="top" width="120"/> 

any idea how implement correctly?

if want make time transaction id can use builtin functionality of core .net framework. one:

datetime.now.millisecond.tostring();