C#

string text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Mauris ut dui vitae nulla eleifend malesuada. Aliquam semper tortor nec arcu. Donec consequat tincidunt ipsum. Praesent tempor magna nec massa. Curabitur ut tortor. Fusce massa. Pellentesque vulputate, ante quis mattis euismod, magna elit pretium enim, eu varius nisl eros vel nisl. Pellentesque quis enim. Phasellus eu erat. Ut convallis pede quis purus. Aliquam nec diam ut mauris congue suscipit. Nam eleifend congue sapien. Cras vulputate erat id ligula. Suspendisse potenti. Sed laoreet aliquet lorem.";

// Count
Hashtable charCounter = new Hashtable();
foreach(char c in text.ToCharArray())
{
	if (charCounter.ContainsKey(c))
	{
		charCounter[c] = (int)charCounter[c] + 1;
	}
	else
	{
		charCounter.Add(c, 0);
	}
}
// Test
foreach(char c in charCounter.Keys)
{
	System.Diagnostics.Trace.WriteLine("Char: " + c + " " + charCounter[c]);
}

blah' AND 1=1; DROP TABLE YourTable; --

public class Tasks
{
	public static void ForceControlValidation(Control c)
	{
		Type t = typeof(Control);

		// validate:
		MethodInfo m = t.GetMethod("NotifyValidating", BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic);
		object obj = m.Invoke(c, new object[0]);

		// finish validating
		if (obj is bool && (bool)obj == false)
		{
			MethodInfo m2 = t.GetMethod("NotifyValidated", BindingFlags.Instance | BindingFlags.InvokeMethod | BindingFlags.NonPublic);
			m2.Invoke(c, new object[0]);
		}
	}
}

public void ValidateFocusedControl()
{
    foreach(Control ctl in Controls)
        if(ValidateFocusedControlRecursive(ctl))
            break;
}

bool ValidateFocusedControlRecursive(Control ctl)
{
    if(ctl.Focused)
    {
        if(ctl.CausesValidation)
        {
            CancelEventArgs cea = new CancelEventArgs();
            cea.Cancel = false;

            ctl.Validating(ctl, cea);  // ***** COMPILE ERROR HERE ******
            if(cea.Cancel != true)
                ctl.Validated(ctl, new EventArgs());
        }
        return true;
    }

    foreach(Control ctl2 in ctl.Controls)
        if(ValidateFocusedControlRecursive(ctl2))
            return true;

    return false;
}

Control active = ActiveControl; // called from within your Form
Control next = active.GetNextControl(active, false); // search backward*
next.Focus();
active.Focus();

public void ValidateFocusedControl()
{
    foreach(Control ctl in Controls)
        if(ValidateFocusedControlRecursive(ctl))
            break;
}

bool ValidateFocusedControlRecursive(Control ctl)
{
    if(ctl.Focused)
    {
        if(ctl.CausesValidation)
        {
            // Make current focused control lose focus, and then get
            // it back, so we can force its validation
            TextBox txtBox = new TextBox();
            txtBox.Bounds = new Rectangle(-100, -100, 1, 1);
            txtBox.Parent = ctl.Parent;
            txtBox.Focus();
            ctl.Focus();
            txtBox.Parent = null;
            txtBox.Dispose();
        }
        return true;
    }

    foreach(Control ctl2 in ctl.Controls)
        if(ValidateFocusedControlRecursive(ctl2))
            return true;

    return false;
}