Integer values are being reset to 0 when the sub in which they are assigned values is ended

In the following code I have two class scoped variables intCompanyID and intEmployeeID. When I set them to a value in btnFetch_Click then try to read them later in btnSubmit_Click they are set to zero.

Why is this?

Option Explicit On
Imports MySql.Data.MySqlClient
Imports System.Data

Public Class EmployeeQuestionaire
Inherits System.Web.UI.Page

Dim intCompanyID A开发者_StackOverflows Integer

Dim intEmployeeID As Integer

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) 
    Handles Me.Load

End Sub

Protected Sub btnFetch_Click(ByVal sender As Object, ByVal e As EventArgs) 
    Handles btnFetch.Click

    intEmployeeID = Convert.ToInt32(txtUserID.Text)
    intCompanyID = 1

    msgbox (intEmpoyeeID & " " & intCompanyID)  '  this shows the values
End Sub

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs) 
    Handles btnSubmit.Click

    MsgBox(intCompanyID & " " & intEmployeeID) 'shows O O
End Sub

ASP.NET will not store any state in between trips to the web-server. Therefore, you will need to find somewhere to store your values. You can use the Session object:

Protected Sub btnFetch_Click
    Session ("MyEmployeeId") = Convert.ToInt32(txtUserID.Text)
End Sub

Protected Sub btnSubmit_Click
    intEmployeeID = Session("MyEmployeeId")
End Sub

Alternatively, you can re-read the txtUserId each time:

Protected Sub btnFetch_Click
    intEmployeeid = Convert.ToInt32(txtUserID.Text)
End Sub

Protected Sub btnSubmit_Click
    intEmployeeID = Convert.ToInt32(txtUserID.Text)
End Sub

There are many other ways, but ultimately I think you need a much better basic understanding of ASP.NET. It's very different to WinForms programming, or whatever you've used. For one, you really shouldn't use MsgBox as your code will generally be running on a web-server with no-one to click "OK"!

Every time a page is posted back, the ASP.NET create the page object and generates all the controls and variables you have defined so you need to use ASP.NET state management technique to preserve the state between requests.

For instance,

  Protected Sub btnFetch_Click(ByVal sender As Object, ByVal e As EventArgs) 
    Handles btnFetch.Click
    int intEmployeeID;
    int.TryParse(txtUserID.Text,out intEmployeeID);
    Session("intCompanyID")=1
    Session("intEmployeeID")=intEmployeeID;
    msgbox (intEmpoyeeID & " " & Session("intCompanyID")) 
End Sub

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs) 
    Handles btnSubmit.Click
    If Not IsNothing(Session("intCompanyID")) Then
      MsgBox(Session("intCompanyID) & " " & Session("intEmployeeID")) 
    End If
End Sub