some stuff i want to know about collections

[nareth]

is a collection faster than an array?
and wasnt there a find member, or was that in a difrent type of collection...?

[dglienna]

just a guess, but I'd imagine that an array would be faster, as it is in the same memory location.

[nareth]

same memory location...?

[dglienna]

contiguous memory location? anyway, once they are initialized, arrays just have a pointer that jumps the same number of bytes to the next value.

[nareth]

i like the remove member of a collection it helps me out alot. but is it alot slower than arrays or jsut a few ms?

[Frans C]

The advantage of a collection is that you can also find an item by it's key. Arrays only have an index.
If you want to find an element in an array without knowing the index, you would have to loop through the array. This can take longer then accessing an item in a collection by it's key.

[nareth]

i dont see a find member how do i search for key...?

[Frans C]

You can access an element of a collection by either it's index or it's key

eg

Dim colCustomers As Collection
Set colCustomers = New Collection
colCustomers.Add "Frans Claessen", "Frans"
MsgBox colCustomers(1)
MsgBox colCustomers("Frans")

[nareth]

oooh ok. thanks this helps ALOOOT


so is it very slower than array or not?

[nareth]

omg arrays are SLOWER!!!!!!

Private Sub Form_Load()
    Dim I As Long
    Dim A As Collection
    Set A = New Collection
    Dim B()
    ReDim B(0)
    Dim C As Long
    
    Let C = GetTickCount
    For I = 0 To 100000
        Call A.Add(I, Str(I))
    Next
    Debug.Print "A.A;" & GetTickCount - C
    
    Let C = GetTickCount
    For I = 0 To 100000
        ReDim Preserve B(I)
        Let B(I) = I
    Next
    Debug.Print "B.A;" & GetTickCount - C
End Sub

A.A;953
B.A;1110

[si_the_geek]

omg arrays are SLOWER!!!!!!

only the way you have done it. If you set the array size before the loop ("redim preserve" is very slow) you'll see that filling an array is much quicker.

Accessing items by position is also much faster with arrays than with collections.

Collections do have advantages though, as someone mentioned above you can find an item by it's key without having to loop. Also you can add/remove items in random places within the "list" whilst keeping it contiguous, which you cannot do with arrays (you need to move the rest of the items).

[MartinLiss]

I love collections and I use them a lot, but keep in mind that a collection will take up more space than an array with same number of entries.

[nareth]

only the way you have done it. If you set the array size before the loop ("redim preserve" is very slow) you'll see that filling an array is much quicker.

Accessing items by position is also much faster with arrays than with collections.

Collections do have advantages though, as someone mentioned above you can find an item by it's key without having to loop. Also you can add/remove items in random places within the "list" whilst keeping it contiguous, which you cannot do with arrays (you need to move the rest of the items).

a collection is dynamic so the array should be dynamic to or else to test is not fair

[David.Poundall]

I just ran your code nareth and got

A.A;2163
B.A;1933

Not much in it I have to admit BUT arrays showed up faster. BTW

Call A.Add(I, Str(I))

needed to be

Call A.Add(I, CStr(I))

Interesting though. Thanks for kicking off the thread

[nareth]

Wierd!.....

i modified the code again to be fair 100%

Option Explicit

Private Declare Function GetTickCount Lib "kernel32" () As Long

Private Sub Form_Load()
    Dim I As Long
    Dim A As Collection
    Set A = New Collection
    Dim B()
    Dim C As Long
    
    Let C = GetTickCount
    For I = 0 To 100000
        Call A.Add(I)
    Next
    Debug.Print "A;" & GetTickCount - C
    
    Let C = GetTickCount
    For I = 0 To 100000
        ReDim Preserve B(I)
        Let B(I) = I
    Next
    Debug.Print "A;" & GetTickCount - C
End Sub

guess what i came up with???
A;62
B;1125

[David.Poundall]

lol - you couldn't have. Both Debug prints would have shown A;

[David.Poundall]

Anyway. As I always define Ubound for my arrays, a fairer test (for fairer - read more applicable for everyday use) would have been C; Which as we would expect, comes out quicker. Interestingly enough bearing in mind this link, by a factor of 4. Now how jammy is that ?

Dim I As Long
    Dim A As Collection
    Set A = New Collection
    Dim B()
    Dim C As Long
    
    Let C = GetTickCount
    For I = 0 To 100000
        Call A.Add(I)
    Next
    Debug.Print "A;" & GetTickCount - C
    
    Let C = GetTickCount
    For I = 0 To 100000
        ReDim Preserve B(I)
        B(I) = I
    Next
    Debug.Print "B;" & GetTickCount - C
    
    Let C = GetTickCount
    ReDim B(100000)
    For I = 0 To 100000
        B(I) = I
    Next
    Debug.Print "C;" & GetTickCount - C

A;120
B;1933
C;30

[nareth]

Let C = GetTickCount
ReDim B(100000)
For I = 0 To 100000
B(I) = I
Next
Debug.Print "C;" & GetTickCount - C

is NOT fair because you dont define a ubound to the collection

[nareth]

and you can get the ubound by simply calling UBound(arr)

and collection has betetr functionality

[David.Poundall]

But A anc C compare everyday usage of the two functions.

You would be mad to code redim preserve on every entry, rather you would add X at a time and trim the array at the end. Where X is what you are comfortable with.

Anyway it is horses for courses.

An interesting thread, we should have a few more of these.