How do I use for loop in vb.net something like
dim start as integer Dim customers as New List(Of Customers) Customers=dataAcess.GetCustomers() For each start=500 in Customers.count 'Do something here' Next I want to process some data for each 500 customers.. Please help
First of all, don't create a New list of customers if you're just going to assign a different list to the variable on the next line. That's kinda dumb. Do it like this:
Dim customers As List(Of Customer) = dataAccess.GetCustomers() Then, for the loop you need a plain For loop rather than a For Each. Don't forget to stop before the count of items, since for .Net the first index is 0 instead of 1:
For i As Integer = 500 To Customers.Count -1 ' Do something with Customers(i) here Next i If you're using Visual Studio 2008 or later you could also write it like this:
For Each item As Customer in Customers.Skip(500) ' Do something with "item" here Next Try the following
For Each current In customers ' Do something here Console.WriteLine(current.Name) Next Something like this:-
Dim customers as New List(Of Customer) Customers=dataAcess.GetCustomers() For Each customer AS Customer in Customers '' // do something with the customer object Next Edit
Sounds like you want to select 500 of N items or perhaps the next 500. You could use the LINQ extension methods .Take and/or .Skip to achieve this. Use ToList then to create your list. E.g.:-
Dim customers as List(Of Customer) customers = dataAccess.GetCustomers().Skip(500).Take(500).ToList() If all you want to do enum through the customers then you could dispense with ToList().
'This will start at 500 and process to the end....
for start as integer = 500 to Customers.Count 'process customer.... customer = Customers(start) Next To iterate the entire list:
for each cust as Customer in Customers Next One note.... VB is case insensitive and your sample code seems to use lower case and upper case customers
Dim start as Integer Dim customers as New List(Of Customers) Customers = dataAcess.GetCustomers() For i as Integer = start to Customers.count Step 500 Debug.Print Customers(i).someProperty Do something here Next i I think you need to use the Customer index and Step in 500s. This will only process customer(start), Customer(start+500), Customer(start+1000) etc, not all the customers. Is that what you intend?
I'm not exactly sure what you're trying to do, but maybe you could try this:
Dim count As Integer = 0 Const MAX_CUSTOMERS As Integer = 500 Dim customers As List(Of Customers) = dataAcess.GetCustomers() For Each c As Customer In customers 'do stuff here' c.Name = "Billy" count+=1 If count = MAX_CUSTOMERS Then Exit For Next It's not elegant by any means, but it makes sense and it will work.
Obviously, there is no shortage of variety. I don't recognize your "DataAcess" object type, but if you can pull that table in as a Recordset (i.e. a SQL table) then try this. (Don't forget to return the recordset when your done)
Option Explicit Dim Customers As Recordset Set Customers=currentdb.openrecordset("???") While Customers.EOF=False 'do stuff here using the recordset object 'i.e. Customers.Fields("Name")="Billy" Customers.MoveNext Wend You can either try:
For i As Integer = 500 To (customers.Count -1) ''do something Next Or
For i As Integer = 0 To (customers.Count - 1) step 500 ''do something Next 
