Gridview logic question

Question

Since I am new to working on C# webforms 2010, I have the following questions to ask so I can understand what is occuring in the following code:

1. In the code listed below, what does the '|' mean in the line 'rowState | DataControlRowState.Edit'? In addition can you explain what is occuring in the line of code for 'row = base.CreateRow(rowIndex, dataSourceIndex, rowType, rowState | DataControlRowState.Edit);'

protected override GridViewRow CreateRow(int rowIndex, int dataSourceIndex, DataControlRowType rowType, DataControlRowState rowState)
{
GridViewRow row;

if (this.BulkEdit)
row = base.CreateRow(rowIndex, dataSourceIndex, rowType, rowState | DataControlRowState.Edit);
else
row = base.CreateRow(rowIndex, dataSourceIndex, rowType, rowState);

return row;
}

2. In the aspx file, I see the following Namespace="BulkEditGridView". Can you explain or point me to a reference show I can understand how the "BulkEditGridView" namespace is wired into making the webpage work?

<%@ Page Title="" Language="C#" MasterPageFile="~/ModuleBase.master" AutoEventWireup="true" CodeBehind="Manage.aspx.cs" Inherits="Support.Manage"
<%@ Register Assembly="Support" Namespace="BulkEditGridView" TagPrefix="test" %>

3. When I step through the code, I see the following items being referred to in the .aspx file. Can you explain what is occurring?

Checked='<%# Convert.ToBoolean( Eval ("L")) %>' runat="server" />

The code is called from ' row = base.CreateRow(rowIndex, dataSourceIndex, rowType, rowState | DataControlRowState.Edit);' that was listed above.

Mamta M · Answer

Yes, that's right.

Sie Ste · Answer

I understand why you use a bitwise for RowState and DataControlRowState fields since that is how the data is stored. However to me since I have never worked with bitwise operators, it means pick the value in either RowState or DataControlRowState field. As long as there is a value in  RowState or DataControlRowState then your check is done.
This does not mean RowState AND DataControlRowState have to have values individually correct?

Mamta M · Answer

A RowState can have multiple states which are indicated using bits. The DataControlRowState enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values. So when you use a  bitwise OR (1) with rowState and DataControlRowState.Edit, you are a bitwise OR with their bit values to know  the values of the row state. Depending on the contents of rowState, after the bitwise OR, it may return one or more of the following values:
Normal,Alternate, Selected, Edit, Insert
That's why you need to do the bitwise OR using |. Hope it's clear now.
And for the record, this is what MSDN says:
A row's state can be one or a combination of the DataControlRowState values, so use bitwise operations to determine whether the state of the row includes a DataControlRowState value, rather than an equivalence test.
In the line of code you have given, you are creating a new row with a specific row state.
Hope that helps.