Dynamic Checkbox Issue

[pheonix]

i create dynamic checkboxes in coloum of table(<td id="trial" runat="server"></td>) from selecting quantity from dropdwonlist.
well creating dynmic checkbox is not an issue..

well the issue is tht i am not able to check whether the Checkboxes is checked or not on a Button click....

the functiion used for generating dyamic checkbox..

protected void ddlList_SelectedIndexChanged(object sender, EventArgs e)  
    {
int no=convert.toint32(ddlist.selectedvalue);  
 
 
for(int i=1;i=<no;i++)
{
checkbox ch=new checkbox()
ch.ID="chk_t"+i;
ch.text="trl"
 
trial.controls.add(ch);
 
}
}

the function where i check whether checkboxes is checked

protected void btnSave_Click(object sender, EventArgs e)  
    {  
list<string> status_tn=new list<string>();
 
for (int j = 1; j <= no; j++)
            {
               trialid = "chk_t" + j;
 
 
              CheckBox  checks=(CheckBox)trial.FindControl(trialid);
 
 
 
 
                if (checks.Checked)
                {
 
                    status_tn.Add("Trial");
 
 
                }
}
          }

in this function i get error :
:System.NullReferenceException was unhandled by user code

Message="Object reference not set to an instance of an object."

Source="App_Web_pm_-zh7o"

StackTrace:

at btn_save_Click(Object sender, EventArgs e) in d:\Dot Net App\Talents\types_seeb.aspx.cs:line 325

at System.Web.UI.WebControls.Button.OnClick(EventArgs e)

at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument)

at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(St ring eventArgument)

at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)

at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)

at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

[tkorsano]

only two observations:

1. after calling FindControl, you should code
//---------------------------------------
if (checks != null)
{

if (checks.Checked)
{

status_tn.Add("Trial");


}
}
//---------------------------------------

2. your "no" variable is declared inside ddlList_SelectedIndexChanged. therefore, i don't think its scope goes beyong that method call, so it doesn't exist in btnSave_Click


good luck,

tonci korsano

[almedajohnson]

The code suggested by tkorsano is absolutely right. You can also set the default value so you for checkbox so you can code accordingly.