I've been looking around for this code and no one could provide it. So finally I wrote it. It checks for duplicates in an array and returns true if there are any.
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'**************************************
' Name: (Updated Again) Check for duplicates in an array!
' Description:I've been looking around for this code and no one could provide it. So finally I wrote it. It checks for duplicates in an array and returns true if there are any.
' By: Arthur Chaparyan3
'
' Inputs:The only input required is the array
'
' Returns:Returns True if there are any duplicates and false otherwise
'
' Assumes:You could use this code to generate lottery numbers or check if more than one record of the same name is present...
'
' Side Effects:If used with LARGE (and I mean LARGE as in arrays with hundreds or thousands of items) it will slow down. USE WITH ONE DIMENSIONAL ARRAYS
'
'This code is copyrighted and has' limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=2856&lngWId=1'for details.'**************************************
Public Function AnyDup(NumList As Variant) As Boolean
Dim a As Long, b As Long
'Start the first loop
For a = LBound(NumList) To UBound(NumList)
'Start the second loop (thanks for the suggestions everyone)
For b = a + 1 To UBound(NumList)
'Check if the values are the same
'if they're equal, then we found a duplicate
'tell the user and end the function
If NumList(a) = NumList(b) Then AnyDup = True: Exit Function
Next
Next
End Function
have you tried setting the lower bound of the second for loop to "a". since the first item is already checked through the list you don't have to keep checking it the further down the list you go. it should speed up the function (well just a suggestion don't know if it will work but something i was just thinking about) (If this comment was disrespectful, please report it.)
I've been thinking to this little problem and come with the fastest solution. One of the problem is that the LBound and Ubound are evaluated at each iteration of the loop. Then, the second loop can start at a+1 this way b will never be equal to a and we can remove the if a <> b condition.
This could look like
Dim Lb as long Dim Ub as long
Lb = LBound(NumList) Ub = UBound(NumList)
for a = Lb to Ub -1 'Minus one to 'avoid a + 1 > Ub 'in next loop for b = a + 1 to Ub If NumList(a) = NumList(b) Then AnyDup = True: Exit Function next b next a
'Please note that the use of Variant data type also slow down the processing. 'Also and very important: Ubound and LBound return a long data type !!! a huga array will crash if you Dim a and b as integers. 'I may be forgotting a few other things but I think it will help. (If this comment was disrespectful, please report it.)
I didn't try your code, but I'm sure it works. There is a faster way though, and I'm not sure its what people want to use, but it is fast. It's basically as fast as loading a list, has no lag or loops what so ever. All you do is make the list sorted, then add an index to a list. If the NewIndex - 1 = NewIndex, then its a dupe. If you do a search for my name on this site, you will see two different versions of this code. Dupe Check with no lag =) (If this comment was disrespectful, please report it.)
I agree with Vincent's code b should start from a+1 and to reduce the process, you should assign UBound(NumList) to any variable. This will reduce the overhead. (If this comment was disrespectful, please report it.)
With large lists you lose a lot of functionality but checking the entire list twice. It will take at least the square of the number of items in the array to process the information.
If you sort the array first, then check for sequential duplicates you will save time. (If this comment was disrespectful, please report it.)
good job... just replace ubound and lbound with some variables. Fair enough to give good rating. (If this comment was disrespectful, please report it.)
but if it starts checking for duplicates at a + 1 what about before a. like further down in the list? (If this comment was disrespectful, please report it.)
Great code, I use it in a sorted multi-select listbox to remove dups, hope it works OK.
For a = 0 To List1.ListCount - 1
For b = a + 1 To List1.ListCount - 1
Result = StrComp(List1.List(a), List1.List(b))
If Result = 0 Then
List1.RemoveItem a
a = a - 1
End If
Next b
Next a
Duplicates should probably be an option in the listbox control but that's a different issue.
Thanks :) (If this comment was disrespectful, please report it.)
You can do another thing is sort the array and while parsing in a loop check if the previous element is equal to current. If true, it has duplicates. (If this comment was disrespectful, please report it.)
try to give what contorl or how many label should i use???? (If this comment was disrespectful, please report it.)
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By 8 Users
8/8/1999 9:51:00 AM: 
