C#

void TestAll(int i)
{
    if (i == numberOfItems)
    {
        check(test-set)
        return
    }
    TestAll(i + 1)
    add input[i] to the test-set
    TestAll(i + 1)
    remove input[i] from the test-set
}

char[] b = new char[] { 'A' , 'B' , 'C' , 'D' , 'E' } ;

for ( int i = 1 ; i <= b.Length ; i++ )
{
    foreach ( System.Collections.Generic.IList<char> a in b.Combinations ( i ) )
    {
        foreach ( char c in a )
        {
            System.Console.Write ( "{0} " , c ) ;
        }

        System.Console.WriteLine() ;
    }
}

class ComboSearcher {
  private string[] _arCombos;
  private int[] _arIndeces;
  private string[] _arSourceArray;

  public ComboSearcher(string[] SourceArray) {
    _arSourceArray = SourceArray
  }

  private void AddItemInt(ref int[] ArrayToUpdate, int ItemToAdd) {
    int[] tmpArray;

    tmpArray = new string[ArrayToUpdate.length];

    for(int i=0; i<ArrayToUpdate.length; i++) {
      tmpArray[i] = ArrayToUpdate[i];
    }

    ArrayTuUpdate = tmpArray;
  }

  private void CutArrayInt(ref int[] ArrayToCut, int NewLength) {
    int[] tmpArray;

    tmpArray = new int[NewLength];

    for(int i=0; i<NewLengh; i++) {
      tmpArray[i] = ArrayToCut[i];
    }

    ArrayToCut = tmpArray;
  }

  private void SubCheck(int IndexNumber) {
    int i, j, minCount;

    //initialize _arCombos if it's not yet initialized
    _arCombos = new string[0]

    AddItemInt(_arIndeces, 0);

    if(_arIndeces.lengh > 1) {
      minCount = _arIndeces[_arIndeces.length - 2);
    }
    else {
      minCount = 0;
    }

    for(i=minCount; i<_arSource.length; i++) {
      _arIndeces[IndexNumber] = i;

      //put preparations to assemble combination here

      for(j=0; j<=IndexNumber; j++) {
        //add routine to assemble combination and perform checks here
      }

      if(_arIndeces.length<_arSourceArray.length) { //also add condition to check if the max number of items is reached when applicable
        CutArrayInt(_arIndeces, IndexNumber + 1);
      }
    }
  }

  public string[] Combinations() {
    //calculate max number of items when applicable

    _arCombos = null; //clear combination list

    SubCheck(0);

    return _arCombos
  }
}

ComboSearcher cboSearch;

cboSearch=new ComboSearcher(source);
target=ComboSearcher.Combinations();

public struct Junk
{
    public readonly char First  ;
    public readonly char Second ;

    public Junk
    (
        char First
    ,
        char Second
    )
    {
        this.First  = First  ;
        this.Second = Second ;

        return ;
    }
}

System.Collections.Generic.List<Junk> l =
    new System.Collections.Generic.List<Junk>() ;

l.Add ( new Junk ( '8' , 'T' ) ) ;
l.Add ( new Junk ( '8' , 'L' ) ) ;
l.Add ( new Junk ( 'B' , 'T' ) ) ;
l.Add ( new Junk ( 'B' , 'L' ) ) ;

foreach ( Junk j in l )
{
    System.Console.WriteLine ( "A1{0}XY{1}" , j.First , j.Second ) ;
}