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,.....
In C# (win application) Thanks in advance
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This is like counting integers in base 'n' .. should not be difficult.
: But I need Unique combination and not double(AA,BB) or repeated combinations(AB,BA) -
My first choice would be "use a
CheckedListBox
and let the user make their picks themselves" - this will save their sanity... would you want to look for "ABCEFH" in a long list?).If you want the strings: How about just using binary arithmetic? i.e. use a number (bit-length as per the number of elements), and simply keep incrementing, including the set bits each time? So in C#, for example:
static void Main() { foreach (string value in GetCombinations( "A", "B", "C", "D", "E", "F", "G", "H")) { Console.WriteLine(value); } } static IEnumerable<string> GetCombinations(params string[] tokens) { ulong max = (ulong) 1 << tokens.Length; StringBuilder builder = new StringBuilder(); // test all bitwise combinations for (ulong value = 0; value < max; value++) { builder.Length = 0; ulong tmp = value; // include the tokens for the set bits for (int i = 0; i < tokens.Length; i++) { if ((tmp & (ulong)1) == 1) builder.Append(tokens[i]); tmp >>= 1; } yield return builder.ToString(); } }
If you want the data in the order per your example, LINQ is helpful:
foreach (string value in GetCombinations( "A", "B", "C", "D", "E", "F", "G", "H") .OrderBy(s=>s.Length) .ThenBy(s=>s)) { Console.WriteLine(value); }
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