title: Need recursive function for generating unique combination of strings
body: <p>I have some(say 9, no not definite) unique strings from database(A,B,C,D,E,F,G,H) and I want to create unique combination of these fields to populate the listbox so that user can select single or different combination of these string fields
  like 
  A,B,C,D,E,F,G,H,
  AB,AC,AD,AE,AF,AG,AH,AC,AD,AE,AF,AG,AG,AH,...
  ABC,ABD,ABE,ABF,ABG,ABH,ACD,ACE,ACF,ACG,ACH,.....</p>
  
  <p>In C# (win application)
  Thanks in advance</p>