gridview里自定义个按钮修改内容找不到TEXTBOX得值

[xiaoheilf]

gridview里自定义了个按钮修改内容
想获取TextBox里修改后的值，总是查找不到TextBox,但找Linkbotton都能找到啊，提示
未将对象引用设置到对象的实例
各种方法都想了 我好郁闷啊，搞了一天了 ，求大大懂的解决下好么
主要是实现验证用户是否登录然后动态显示编辑按钮执行编辑

        <asp:GridView ID="GridView1" runat="server" AllowPaging="True" AutoGenerateColumns="False" OnPageIndexChanging="GridView1_PageIndexChanging" OnRowDeleting="GridView1_RowDeleting" OnRowEditing="GridView1_RowEditing" OnRowUpdating="GridView1_RowUpdating" OnSelectedIndexChanging="GridView1_SelectedIndexChanging" PageSize="3" DataKeyNames="tb_ID,tb_Title,tb_Content" OnRowCancelingEdit="GridView1_RowCancelingEdit" Width="660px" BackColor="White" BorderColor="White" BorderStyle="None" BorderWidth="5px" OnRowDataBound="GridView1_RowDataBound" OnRowCommand="GridView1_RowCommand">
            <Columns>
            <asp:TemplateField HeaderText="留言内容" >
                <EditItemTemplate>
                <table>
                                <tr>
                <td>
              留言者 ：
                    <asp:Label ID="Label2" runat="server" Text=<%# Eval("tb_name") %>></asp:Label></td>
                </tr>
                <tr>
                <td>
             留言标题 <asp:TextBox ID="TextBox5"  runat="server" Text='<%# Bind("tb_Title") %>'></asp:TextBox> 
                </td>
                </tr>
                <tr >
                <td>
               留言内容 ：<asp:TextBox ID="TextBox6" runat="server" Text='<%# Bind("tb_content") %>'></asp:TextBox> 
                </td>
                </tr>
                  <tr >
                <td>
               留言回复：<%# Eval("tb_mark") %>
                </td>
                </tr>
                                  <tr>
                <td>
                     <asp:LinkButton ID="LinkButton3" Visible="false" runat="server">编辑</asp:LinkButton>
                    <asp:LinkButton ID="LinkButton4" Visible="false" runat="server">删除</asp:LinkButton>
                    <asp:Label ID="Label1" runat="server" Visible="false" Text=<%# Eval("tb_ID") %>>    </asp:Label>
                    <asp:LinkButton ID="LinkButton5"  Visible="true" OnClick="LinkButton5_Click" CommandName="Edit" CommandArgument=<%# Eval("tb_ID") %> runat="server">111</asp:LinkButton> 
                    <asp:LinkButton ID="LinkButton6" Visible="false" OnClick="LinkButton6_Click" CommandArgument=<%# Eval("tb_ID") %> runat="server" CommandName="Update">保存</asp:LinkButton> 
                    <asp:LinkButton ID="LinkButton7" Visible="false" OnClick="LinkButton7_Click" CommandArgument=<%# Eval("tb_ID") %> runat="server" CommandName="Cancel">取消</asp:LinkButton>
                    <asp:LinkButton ID="LinkButton8" Visible="false" OnClick="LinkButton8_Click" CommandArgument=<%# Eval("tb_ID") %> runat="server" CommandName="Delete">删除</asp:LinkButton>
                    </td>
                       <td style="width: 7px">
                          </td>
                </tr>
                    
                </table>
                </EditItemTemplate>
                
                <ItemTemplate>
                <table>
                                <tr>
                <td style="width: 246px">
              留言者 ：
                    <asp:Label ID="Label2" runat="server" Text=<%# Eval("tb_name") %>></asp:Label></td>
                </tr>
                <tr>
                <td style="width: 246px">
              留言标题 ：<asp:Label ID="Label3" runat="server" Text=<%# Eval("tb_title") %>></asp:Label>
                </td>
                </tr>
                <tr >
                <td style="width: 246px">
               留言内容 ：<asp:Label ID="Label4" runat="server" Text=<%# Eval("tb_content") %>></asp:Label>
                </td>
                </tr>
                  <tr >
                <td style="width: 246px">
               留言回复：<asp:Label ID="Label5" runat="server" Text=<%# Eval("tb_mark") %>></asp:Label>
                </td>
                </tr>
                                  <tr>
                <td style="width: 246px">
                     <asp:LinkButton ID="LinkButton3" Visible="false" runat="server">编辑</asp:LinkButton>
                    <asp:LinkButton ID="LinkButton4" Visible="false" runat="server">删除</asp:LinkButton>
                    <asp:Label ID="Label1" runat="server" Visible="false" Text=<%# Eval("tb_ID") %>>    </asp:Label>
                    <asp:LinkButton ID="LinkButton5" Visible ="true" OnClick="LinkButton5_Click" CommandName="Edit" runat="server" CommandArgument=<%# Eval("tb_ID") %>></asp:LinkButton>
                    <asp:LinkButton ID="LinkButton6"  OnClick="LinkButton6_Click" CommandArgument=<%# Eval("tb_ID") %> runat="server" CommandName="Update"></asp:LinkButton>
                    <asp:LinkButton ID="LinkButton7"  OnClick="LinkButton7_Click" CommandArgument=<%# Eval("tb_ID") %> runat="server" CommandName="Cancel"></asp:LinkButton>
                    <asp:LinkButton ID="LinkButton8"  OnClick="LinkButton8_Click" CommandArgument=<%# Eval("tb_ID") %> runat="server" CommandName="Delete"></asp:LinkButton>
                    </td>
                       <td style="width: 7px">
                          </td>
                </tr>
                    
                </table>
                </ItemTemplate>
           </asp:TemplateField>

                           </Columns>
                           
        </asp:GridView>
  

    protected void LinkButton6_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < GridView1.Rows.Count; ++i)
        {
                      
            string xx= ((TextBox)GridView1.Rows[i].FindControl("TextBox5")).Text;
             Response.Write(xx);
            //string tbtstr = tbt1.Text;
           // TextBox str = (TextBox)(GridView1.Rows[2].FindControl("TextBox5"));也不行
        }
    }
  

[PandaIT]

GridView.Rows[].Cells[].FindControl//换成这个

[孟子E章]

TextBox5只是在编辑的行里才有的，不是每个都有
for (int i = 0; i < GridView1.Rows.Count; ++i)
这么遍历肯定是不行，你只能找你编辑的那行的index

可以参考这个
http://dotnet.aspx.cc/file/Add-Delete-Update-Edit-Data-With-Paging-in-GridView.aspx