how to find how many controls are used in the form

In January, 2014, I posted an answer to a CP QA question that shows how to get all the Controls using a 'Stack, rather than using the usual recursive technique: [^].

That answer has complete source code, and examples, and links to where I got the idea from, and links to discussion of using the Stack based technique by people much smarter than I will ever be.

Modifying this code to build a record of each Control Type found, and a List of instances of each Type of Control can be done like this:

using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

public static class SpecialMethods
{
    // added 12/15/2014 by bw
    public static Dictionary<string,List<Control>> GetControlsByType(Control aControl)
    {
        // see comments
        return GetAllControls(aControl)
            .GroupBy(typ => typ.GetType().Name)
            .Select(grp => grp.ToList())
            .ToDictionary(name => name[0].GetType().Name);
    }

    public static IEnumerable<Control> GetAllControls(Control aControl)
    {
        Stack<Control> stack = new Stack<Control>();
 
        stack.Push(aControl);
 
        while (stack.Any())
        {
            var nextControl = stack.Pop();
 
            foreach (Control childControl in nextControl.Controls) stack.Push(childControl);

            yield return nextControl;
        }
    }
}

Now we can test this using a Form (or any other Control that may have Child Controls):

private void Form1_Load(object sender, EventArgs e)
{
    foreach (KeyValuePair<string,List<Control>> kvp in SpecialMethods.GetControlsByType(this))
    {
        Console.WriteLine("Control Type: {0} Count: {1}", kvp.Key, kvp.Value.Count.ToString());
    }
}

Here's a sample output from a test:

Control Type: Form1 Count: 1
Control Type: ToolStrip Count: 2
Control Type: Button Count: 4
Control Type: TextBox Count: 1
Control Type: Label Count: 3
Control Type: GroupBox Count: 1
Control Type: Panel Count: 2

Comments:

What's happening in the 'GetControlsByType static method:

1. all the Controls are filtered into a set of IGroupings based on the name of the Type of each Control: by the GroupBy operation

2. each IGrouping is transformed into a List<Control> by the 'Select operation.

3. a Dictionary is created with the key set to the Name of the Type of the first Control in each List<Control> in each Group.