C#: Is There A ForAny Statement?

Question

Quick question, I know there is a foreach statement that checks each specified control in a form, but is there a forany statement that can check for a specific control amongst a group of the same types of controls, or is there a certain specification I can use in a foreach state that limits it. For example: Say I check if ANY RadioButton on a form is checked. If one is checked, it a message box will display "Hi". My approach would go something like:

foreach (Control rb in this.Controls.OfType<RadioButton>())
{
    if(((RadioButton(rb)).Checked == true)
    {
        MessageBox.Show("Hi");
        return;
    }
}

The problem with this is it checks ALL RadioButtons and sees if they are checked. I don't want that. I want it to check if anyone of the are checked. Is there a way I can manipulate this?

Answer 1

Linq is your friend here, Use Any() method which will return bool, but behind the scenes of-course it will also loop through the check-boxes it's just syntactic sugar.

Your all this code :

foreach (Control rb in this.Controls.OfType<RadioButton>())
{
    RadioButton rbs = sender as RadioButton();
    if(rbs.Checked == true)
    {
        MessageBox.Show("Hi");
        return;
    }
}

can be replaced with:

var anyRadioChecked = this.Controls.OfType<RadioButton>().Any(x=>x.Checked);
if(anyRadioButton)
{
   MessageBox.Show("Hi");
   return;
} 

and if you are inside a RadioButton event, and you want to check for the RadioButton is checked only if there is any RadioButton on the Form then you would need to do it following way:

RadioButton rbs = sender as RadioButton;
var anyRadioButton = this.Controls.OfType<RadioButton>().Any();
if(anyRadioButton && rbs.Checked)
{
   MessageBox.Show("Hi");
   return;
} 

The above will return true if atleast one checkbox is checked.

Answer 2

Well, your current code does that already. You only enumerate the collection until the first checked RadioButton. You could use LINQ to shorten the code as Ehsan has already shown.

But is there a forany statement

This sounds like you want to use seomething like this:

var checkedRadioButtons = this.Controls.OfType<RadioButton>().Where(cb => cb.Checked);

Now you can enumerate all checked radio-buttons:

foreach(RadioButton btn in checkedRadioButtons)
{
    // ..
}

or if you only want to know if there is at least one:

bool isAnyCheckedRadioButton = checkedRadioButtons.Any();

or you want to know how many are checked:

int countCheckedRadioButtons = checkedRadioButtons.Count();

or you want to store them in a collection:

List<RadioButton> checkedRadioButtonList = checkedRadioButtons.ToList();

Maybe that LINQ query using Enumerable.Where is what you understand as ForAny:

Answer 3

You could create your own extension method to do it - that's all ForEach, Select etc. are.

public static class EnumerableExtensions
{
    public static void ForFirst<T>(this IEnumerable<T> arr, Func<T, bool> predicate, Action<T> action)
    {
        using (var enumerator = arr.GetEnumerator())
        {
            while (enumerator.MoveNext())
            {
                if (predicate(enumerator.Current))
                {
                    action(enumerator.Current);
                    return;
                }
            }
        }
    }
}

Usage:

this.Controls.OfType<RadioButton>()
    .ForFirst(
        rb => rb.Checked, 
        rb => MessageBox.Show("Hi from " + rb.ToString()));

You can use First(), Where(), Any() I have just offered a different but valid solution. This is solution is flexible, and a one liner...