Hi,
Try this,
char[] separator = new char[] { '\\' };
string[] new_x= x.Split(separator,3);
It will split ur String ( i.e x)into 3 parts i.e new_x[0],new_x[1],new_x[2].
check which string of array contains ur answer and just use it.
I think in ur case new_x[1] will hold ur username.
Or
refer this link
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