A very simple c# question (Button doesnt increment textbox value)

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This seems pretty straightforward .

I am trying to create a simple asp.net webform with textbox and button.

Whenever i should hit click button, the value in textbox should increment by 1 . Here's my code

C#

public partial class WebForm1 : System.Web.UI.Page
{
    int clickload = 1;
    protected void Page_Load(object sender, EventArgs e)
    {
        if(!IsPostBack)
        {
            TextBox1.Text = "0";
        }

    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        if (ViewState["clicks"] != null)
        {
            clickload = (int)ViewState["Clicks"]+1;

        }

            TextBox1.Text = clickload.ToString();

            ViewState["clicks"] = clickload;


    }

But, when i run it. It shows me 1 correctly , but then it throws me this error

http://postimg.org/image/elosn84wr/[^]

can someone tell me whats wrong with the code?

Thanks

Posted 21-May-15 23:46pm

ankur1163

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4 solutions

Solution 2

Hi,

I can't see the image that contains the error detail, but I suspect your issue is related to the ViewState Key being case sensitive.

C#

ViewState["Clicks"]

is not that same as:

C#

ViewState["clicks"]

C#

protected void Button1_Click(object sender, EventArgs e)
{
    if (ViewState["clicks"] != null)
    {
        clickload = (int)ViewState["clicks"]+1;
    }
    TextBox1.Text = clickload.ToString();
    ViewState["clicks"] = clickload;
}

... hope it helps.

Posted 22-May-15 0:04am

hypermellow

Solution 3

why you use viewstate at all? it is not necessary, just use update panel to update the textbox with the new value
here is the code

code behind:

C#

protected void Page_Load(object sender, EventArgs e)
   {
       if (!IsPostBack)
       {
           txtnumber.Text = "0";

       }
   }
   protected void Button1_Click(object sender, EventArgs e)
   {
       int number;
       number = int.Parse(txtnumber.Text);
       number++;
       txtnumber.Text = number.ToString();

   }

html :

XML

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
        <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:TextBox ID="txtnumber" runat="server"></asp:TextBox>
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
            </Triggers>
        </asp:UpdatePanel>
    </div>
    </form>
</body>
</html>

let me know if it worked for you, mine was fine
good luck

Posted 22-May-15 0:22am

Saeed Jafarian

Updated 22-May-15 0:23am

v2

Solution 4

The reason seems to be the capital C in

ViewState["Clicks"]

However this can also be done without viewstate like below :

protected void Button1_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(TextBox1.Text))
            {
                int clicks = 0;
                Int32.TryParse(TextBox1.Text ,out clicks);
                TextBox1.Text  = (clicks + 1).ToString();
            } 

        }

Posted 22-May-15 1:00am

ConnectingKamlesh

Updated 22-May-15 1:01am

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DamithSL · Accepted Answer · 2015-05-22T00:00:00

Solution 1

you have capital C in the Clicks (view state key name) but when you set you have simple c. make it simple and try again.
viewState Key Name is case sensitive

C#

if (ViewState["clicks"] != null)
{
  clickload = (int)ViewState["clicks"]+1;           
}

Posted 22-May-15 0:00am

DamithSL

Updated 22-May-15 0:05am

v2

Comments

hypermellow 22-May-15 6:05am

Beat me to it! 5+