implementing CheckBox check in GridView with ASP.NET (C#)

Question

Greetigs fellow programmers! I have a question for you about the implementation of a CheckBox check across a Gridview. First of all, the Gridview is binded to a different datasource according to the querystring that links to the page. This is working so far, i see different elements by different querystrings. What the problem is, and i cannot yet detect how to fix, is that if i select let's say 3 out of 4 checkboxes and press and button that verifies the selections (writes selections to textbox), the program AUTOMATICALLY CHECKS ALL the checkboxes and gives me all the values (which i don't need) . I browsed for answers but could not find something similar (or i didn't search good enough,w/e). Could some kind fellow programmer maybe explain what the mistake is, how to guard from possible bugs, or indicenter code hereate the changes i need to do?

The code for the Gridview:

<asp:GridView ID="Foods" runat="server">
<Columns>
    <asp:TemplateField>
    <ItemTemplate>
    <asp:CheckBox runat="server" ID="CheckBox1" />
    </ItemTemplate>
    </asp:TemplateField>
    </Columns>
</asp:GridView>

and the C# code: (code is under a Button's onclick method)

String output = "";
foreach (GridViewRow row in Foods.Rows)
{
CheckBox cb = (CheckBox)row.FindControl("CheckBox1");
if ((cb != null) && (cb.Checked = true))
{
output += row.Cells[1].Text.ToString() + ",";
}
}
TextBox1.Text = output;

Any help will be appreciated!

Answer 1

in the C# code

if ((cb != null) && (cb.Checked = true))

this

cb.Checked = true

should be

cb.Checked == true

you are making an assignment, instead of checking the value