Re: Looping through an array with FOR EACH

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Le 16/01/2026 à 00:21, Gianluigi a écrit :
> Dear Benoit,
>
> I apologize for creating all this confusion.
>
> It all started with a forum user writing that it would have been better 
> to loop through the array with For Each.
> Then I remembered your warning (which, as usual, I misunderstood).
>
> But at this point, you need to explain to me why the FOR EACH loop would 
> be better than the one I suggested:
>
> [code] Public Sub Main()
>
>    Dim aAreas As New String[][] ' The dynamic matrix
>    Dim r, c, e, i As Integer
>    ' Array of support to the random filling of the matrix with pseudo names
>    Dim aNomi As String[] = ["Ful", "Gal", "Doc", "Ech", "All", "Bil", 
> "Val", "Mal", "Cec", "Lol", "Nib"]
>
>    r = 5 ' six rows
>    ' Initializes the random number generator
>    Randomize
>    ' Loop to populate the dynamic array
>    For e = 0 To r
>      ' Resize the array
>      aAreas.Resize(e + 1)
>      ' Instantiates a new internal array
>      aAreas[e] = New String[]
>      ' random number of columns
>      c = Rand(0, 8)
>      ' Loop to populate the array
>      For i = 0 To c
>        ' Resize the array
>        aAreas[e].Resize(i + 1)
>        ' Generate random names, but with number of row and column for 
> the control
>         aAreas[e][i] = aNomi[Rand(0, 10)] & "(C" & CStr(i + 1) & " R" & 
> CStr(e + 1) & ")"
>      Next
>    Next
>    ' Read the jagged matrix
>    For r = 0 To aAreas.Max
>      For c = 0 To aAreas[r].Max
>        Print aAreas[r][c];;
>      Next
>      Print
>    Next
>
>    ' This may be better <----------------------???
>    Print "=============================================================="
>    For Each area As String[] In aAreas
>          For Each entry As String In area
>              Print entry;;
>          Next
>          Print
>      Next
>
> End [/code]
>
> With Best Regards
> Gianluigi

Better for what?

"For Each" on an array is usually slower than using a "For...To" loop 
with an index variable, except if you don't need the index. Check by 
yourself anyway according to what you need exactly.

And the JIT compiler do not optimize the "For Each" loop.

Otherwise it's not important how you browse the array.

Regards,

--
Benoît Minisini.