How do I resolve index -5 is either negative or above rows count.

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I am trying to modify my datalist view to have paging , I used the below code which I found on c-sharpconer, but I get error message when I click on the previous buttons, all other buttons work work.
The error message says:

Quote:
Index -5 is either negative or above rows count.

This is my aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="PagininDataList.WebForm1" %> 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style type="text/css">
        .style1
        {
            width: 672px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
   <div>
    <table style="height: 79px; width: 429px">
        <asp:DataList ID="DataList1" runat="server">
        <HeaderTemplate>
        <h1> Details </h1>
        </HeaderTemplate>
      <ItemTemplate>
        <tr>

        My Custom Datalist Template here
        </tr>

        </ItemTemplate>
        </asp:DataList>
       </table>
   <table>
  <tr>
    <td>
        <asp:Button ID="btnfirst" runat="server" Font-Bold="true" Text="<<" Height="31px"
                    Width="43px" onclick="btnfirst_Click" /></td>
        <td>
            <asp:Button ID="btnprevious" runat="server" Font-Bold="true" Text="<" Height="31px"
                    Width="43px" onclick="btnprevious_Click" /></td>
            <td>
                <asp:Button ID="btnnext" runat="server" Font-Bold="true" Text=">" Height="31px"
                    Width="43px" onclick="btnnext_Click" /></td>
                <td>
                    <asp:Button ID="btnlast" runat="server" Font-Bold="true" Text=">>" Height="31px"
                    Width="43px" onclick="btnlast_Click" /></td>
    </tr>
   </table>
    </div>
    </form>
</body>
</html>

this is my C# code

namespace PagininDataList
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        SqlDataAdapter dadapter;
        DataSet dset;
        PagedDataSource adsource = new PagedDataSource();
        string connstring = "My connection string";
        int pos;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                this.ViewState["vs"] = 0;
            }
            pos = (int)this.ViewState["vs"];        
            databind();
        }             
        public void databind()
        {
            dadapter = new SqlDataAdapter("my SELECT query", connstring);
            dset = new DataSet();
            
            dadapter.Fill(dset);
            adsource.DataSource = dset.Tables[0].DefaultView;
            adsource.PageSize = 3;
            adsource.AllowPaging=true;
            adsource.CurrentPageIndex = pos;
            btnfirst.Enabled = !adsource.IsFirstPage;
            btnprevious.Enabled = !adsource.IsFirstPage;
            btnlast.Enabled = !adsource.IsLastPage;
            btnnext.Enabled = !adsource.IsLastPage;
            DataList1.DataSource = adsource;
            DataList1.DataBind(); 
        }
 
        protected void btnfirst_Click(object sender, EventArgs e)
        {
            pos = 0; 
            this.ViewState["vs"] = 0; 
            databind();
        }
 
        protected void btnprevious_Click(object sender, EventArgs e)
        {
            pos = (int)this.ViewState["vs"];
            pos -= 1;
            this.ViewState["vs"] = pos;
            databind();
        }
 
        protected void btnnext_Click(object sender, EventArgs e)
        {
            pos = (int)this.ViewState["vs"];
            pos += 1;
            this.ViewState["vs"] = pos;
            databind();
        }
 
        protected void btnlast_Click(object sender, EventArgs e)
        {
            pos = adsource.PageCount - 1; 
        this.ViewState["vs"] = pos; 
        databind(); 
        }
    }
}

What I have tried:

I try changing the page size, but it still give the error.

Posted 22-Sep-17 23:30pm

Vixita-i50

Updated 22-Sep-17 23:35pm

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Comments

Richard MacCutchan 23-Sep-17 6:24am

Well -5 is definitely negative, so you need to find out how it got that value, and fix your code.

1 solution

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OriginalGriff · Answer 1 · 2017-09-22T23:35:00

Solution 1

Well ... if you found the code on csharp corner, then the obvious thing to do is: ask there.
Talk to the author, explain your problem, see how much help he can be.

Asking at a random site for support on software from a different site isn't the most sensible way to get started...

Posted 22-Sep-17 23:35pm

OriginalGriff