Windows Forms - Iterating through controls on a form

Daniel

I have a form with many groupboxes (18) and within each groupbox are controls (textboxes and checkboxes). When the user clicks the "NEW" button, I want to clear all controls on the form for data entry. I figured I would generically iterate through all the controls on the form and clear the information accordingly (set textbox.text = "" or checkbox.checked == false). I can get to all the groupboxes but can figure out how to iterate the controls within each groupbox. Here is my psuedo code: foreach (Control c in this.Controls) { //check for a groupbox if (c is GroupBox) { } }

6 Replies

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Alan19y ago
I typed it into Notepad first and then pasted it in from there.
Daniel19y ago
How do you get the code you pasted in to be formatted correctly. It looks like mine is getting garbled.
Daniel19y ago
Thanks for the info. I played around with some other ways and got this to work also: //iterate through the form controls foreach (Control c in this.Controls) { //check for a groupbox if (c is GroupBox) { //go through each control in the groupbox for (int iCount = 0; iCount < c.Controls.Count; iCount++) { //get the control type string strType = c.Controls[iCount].GetType().ToString().Substring(c.Controls[iCount].GetType().ToString().LastIndexOf(".") + 1); //create temp control to cast the control type. Control cc = c.Controls[iCount]; switch (strType) { case "TextBox": TextBox tb = (TextBox)cc; tb.Enabled = true; tb.Text = ""; break; case "CheckBox": CheckBox cb = (CheckBox)cc; cb.Checked = false; break; case "MaskedTextBox": MaskedTextBox mcb = (MaskedTextBox)cc; mcb.Enabled = true; mcb.Text = ""; break; } } }
Alan19y ago
In this line 'c' is a variable of type Control but actually contains an object of type GroupBox which is derived from Control:

GroupBox gb = (GroupBox)c;

To assign 'c' to the GroupBox variable, we have to cast it to it's actual type and so, yes (GroupBox) means cast the following expression to GroupBox. If you didn't use the cast, you'd find that the compiler would complain that there is no implicit conversion from Control to GroupBox.

You can only use a 'switch' statement with variables of bool, string or one of the integer types (including enums), so it's better to use an 'if' statement here.
Daniel19y ago
Thanks for the quick response. I did try that and it seems to work. Being relatively new to C# syntax, I have a question about syntax. Can you tell me what wrapping a control in parenthesis next to another object does? Casting? (GroupBox)c (TextBox)cc Any reason not to use a switch statement? Thanks again!
Alan19y ago
See if this will work:

foreach (Control c in this.Controls)
{
    if (c is GroupBox)
    {
        GroupBox gb = (GroupBox)c;
        foreach(Control cc in gb.Controls)
        {
           if(cc is TextBox)
           {
              TextBox tb = (TextBox)cc;
              tb.Text = "";
           }
           else if (cc is CheckBox)
           {
              CheckBox cb = (CheckBox)cc;
              cb.Checked = false;
           }
        }
     }
}