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Question

how to loop through some ASP.NET labels to set their attributes?

Answer 1

+2 A:

You can access a control by its name using

container.Controls["nameofcontrol"]

So technically, you could use this to lookup your control

(Untested code)

for(int index = 1; index <= Convert.ToInt32(ddlTool.SelectedValue); index++)
{
    this.Controls["lblTool" + index.ToString()].Visible = true;
    this.Controls["txtTool" + index.ToString()].Visible = true;
}

Pierre-Alain Vigeant 2010-05-26 19:02:22

Answer 2

+1 A:

Use a UserControl for each set of connected controls and then enable/disable the UserControl instead of all the component controls. This is classic, basic modularization of your user interface.

Note that this will still require a little "redundant" code because you're working with an unusual UI paradigm by enabling up-to the ddlTool's selected value of your control. E.g., create your user control that contains a single Label and TextBox. Call it LabeledTextBox or something similar. Then you'd create a collection of your labeled text boxes and enable them up to int.Parse(ddlTool.SelectedValue) - 1.

Greg D 2010-05-26 19:02:51

Answer 3

A:

foreach (Control ctrl in this.Controls)
{
    int index = (int)ctrl.Name.Substring(ctrl.Name.Length - 1);
    int maxIndex = (int)ddlTool.SelectedValue;
    ctrl.Visible = (index <= maxIndex);
}

MusiGenesis 2010-05-26 19:02:58

Answer 4

+7 A:

Instead of having a separate variable for each textbox and label, have a collection of them - whether that's a List<T> or an array or whatever.

Then you can do:

// Potentially use int.TryParse here instead
int visibleLabels = int.Parse(ddlTool.SelectedValue);
for (int i = 0; i < labels.Count; i++)
{
    labels[i].Visible = (i < visibleLabels);
    textBoxes[i].Visible = (i < visibleLabels);
}

(Alternatively use two loops, one to set some Visible properties to true, and one to set some to false.)

Jon Skeet 2010-05-26 19:03:38

Since it's not obvious from the original description whether this is about Windows Forms or ASP.NET, I'll explain for both: make sure you initialize the array only once the controls are created (on Windows Forms, it's after the call to InitializeComponent(); on ASP.NET; it's after FrameworkInitialize(), so usually in the Load event). A better solution would be to use properties to initialize the arrays on first access only, potentially using .NET 4' new Lazy<T> class if you can.

Francis Gagné 2010-05-26 19:11:15

Since control arrays aren't natively supported I thought this article about Creating Control Arrays in .NET would be a useful supplement: http://msdn.microsoft.com/en-us/library/aa289500%28VS.71%29.aspx

Sorax 2010-05-26 19:19:15

Answer 5

A:

Here is an example with no error checking, but should match your code functionality.

protected void ddlTool_SelectedIndexChanged(object sender, EventArgs e) 
{
  int selectedValue = int.Parse(ddlTool.SelectedValue.ToString());
  for (int i = 1; i <= 4; ++i)
  {
    bool state = i <= selectedValue;
    this.Controls["lblTool" + i.ToString()].Visible = state;
    this.Controls["txtTool" + i.ToString()].Visible = state;
  }
}

Chris Taylor 2010-05-26 19:06:11

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