please tell me what is the function of DataBinder and what is the function of Eval() method. what kind of job it does.
explain me in detail with example.

When you use a web control such as a datalist or datagrid you would normally set the datasource for this data display control to be a dataset or repeater.

// ds is your dataset and MyDataGrid is your datagrid MyDataGrid.DataSource = ds; MyDataGrid.DataBind();

These ADO.NET components will naturally have different fields that hold the data. You want to be able to resolve matching fields from your datasource to your control. The DataBinder class helps you to do this. It is from the System.Web.UI . the Eval method is an overloaded method of this class that allows you to evaluate and resolve an expression to  an object at run time. You will be able to call the proper field from your datasource and bind it to the appropriate filed in your display control.

Here is an example

\\this piece of code resolves the datafield Price in the datasource to the label in the itemteplate of MyDataGrid <asp:Label ID="mylabel"><%# DataBinder.Eval(Container.DataItem, "Price", "{0:c}") %></asp:Label>

DataBinder.Eval() method will also do type cats/conversion implicitly for yu

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BrainBench ADO.NET and ASP.NET Certified Developer

A followup question on this.. I know is many moons later.
Qustion How does the .Eval(Container.Data)  make the connection to the dataset... there does not seem to be reference to the data set in the <%#DataBinder.Eval(Container.ItemData("Person")%> there could be multiple dataset binds.  So it is not clear how this statement makes the association on the Server to the correct dataset

Thanks

ben

The association is made when the databind method is calles on the datagrid

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BrainBench ADO.NET and ASP.NET Certified Developer