Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index VB.NET

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 Sub read()
        Dim constring As String = "dsn=mysql_tabel;database=db1;server=localhost;iud=root"
        Dim con As New OdbcConnection(constring)
        'Dim con As New OdbcCommand(SQL)
        'dataload()
        con.Open()
        Dim query As String = "Select *From tbdata_reservasi"
        Dim cmd As New OdbcCommand(query, con)
        Dim dr As OdbcDataReader = cmd.ExecuteReader()

        While dr.Read
            Dim RoomNum_R As Integer = dr.GetInt32(7)
            Dim startdate As DateTime = dr.GetDate(9)
            Dim enddate As DateTime = dr.GetDate(10)

            Dim startdate_c As Integer = startdate.Day
            Dim enddate_c As Integer = enddate.Day
            Dim room1 As Integer = RoomNum_R - 1 
            Dim totaldays As Integer = enddate_c - startdate_c

            DG1(startdate_c, room1).Style.BackColor = Color.Red

            For i = 1 To totaldays
                DG1(startdate_c + i, room1).Style.BackColor = Color.Red

                totaldays -= 1
                'totaldays = -1

            Next

        End While
    End Sub

What I have tried:

i dont know for solution,if the number of RoomNum only 1 digit there is no error,but if mor digit at the RoomNum it will be error "<pre>Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index"

Posted 22-May-23 0:55am

Joebpn1

Updated 22-May-23 1:54am

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CPallini · Answer 1 · 2023-05-22T01:05:00

Solution 1

It looks your DG1 array (whatever it is) has not enough rooms... :-)
I suggest you to use the debugger to gain some insight.

Posted 22-May-23 1:05am

CPallini

Comments

Joebpn1 22-May-23 7:41am

DG1 is gridview1

Joebpn1 22-May-23 7:49am

can you help for the array?

OriginalGriff · Answer 2 · 2023-05-22T01:54:00

At a guess, DG1 is a DataGrid of some form, and you are trying to set the background colour for rooms, but boy are there problems with that code ...
Your For loop runs from 1 (which isn't the index of the first row - they are numbered from 0 in .NET) to a value that you decrease each time you go round it ...

Instead of playing with the colours, do it when you draw the control - this may help: Colouring DataGridView Cells According to their Content in WinForms[^] the code is in C#, but onlone converters exist and can help you you don't understand: Code Converter C# to VB and VB to C# – Telerik[^]