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Shurik76 on 02/26/09

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# Array Shuffle (w. downsize)

/ Published in: ASP  `' This function will DEAL the "needed"' number of values from the given "inArray"'' If the value for "needed" matches the' upper bound of the "inArray", then the' entire "inArray" is dealt out.'' NOTE: As written, this code never uses' or touches element zero of the inArray' and puts no value in element zero of the' outArray. (Obviously, easy to change.)'Function Shuffle( inArray, needed )    ' find out how many input elements there are...    incnt = UBound( inArray )    ' then create the output array to be the size    ' requested via the "needed" argument    dim outArray    redim outArray( needed )     ' now we will select the number of values    ' specified as "needed"...    For i = 1 To needed        ' choose a random number from 1 to our        ' current input array usage size...        choose = Int( incnt * Rnd(1) ) + 1         ' put that chosen element into the next        ' slot in the output array...        outArray( i ) = inArray( choose )         ' here's the tricky part: Since we just        ' used the "choose" element, we don't need        ' it any more...we replace it with the last        ' element of the in-use part of the array!        inArray( choose ) = inArray( incnt )         ' and then we (effectively) shrink the array!        ' Next time through the loop, there will be        ' one fewer elements in the array to choose        ' from...because we have (effectively) deleted        ' the one just chosen!        incnt = incnt - 1     Next    ' return the shuffled output    Shuffle = outArrayEnd Function ' This is just a convenience function'' If you need *all* the "cards" in a deck of a given' size shuffled, and the "name" of a card can just be' its numeric position in the unshuffled deck, then' just call ShuffleDeck, passing the size of the deck' to be shuffled.'Function ShuffleDeck( deckSize )    Dim i, deck()    ReDim deck( deckSize )    For i = 1 To deckSize        deck(i) = i    Next    ShuffleDeck = Shuffle( deck, deckSize )End Function%> <HTML><BODY> <%Randomize ar = Array(0,"you","can","put","anything","in","the","array","of","course")str = Mid( Join(ar," "), 2 )Response.Write "Picking 4 words from this list: <STRONG>" _             & str & "</STRONG><OL>" & vbNewLinesh = Shuffle( ar, 4 )For i = 1 to 4    Response.Write "<LI>" & sh(i) & vbNewLineNext Response.Write "</OL><P> <P>" & vbNewLine Response.Write "Shuffling a 'deck' of 20 numbered cards.<BR>" _            & "The cards were originally numbered from 1 to 20.<P>" & vbNewLinesh = ShuffleDeck( 20 )str = Mid( Join( sh, "," ), 2 )Response.Write "The shuffled deck: <STRONG>" & str & "</STRONG>" & vbNewLine%>` Subscribe to comments