InputUtils.cs

using System;
using System.Collection.Generic;
using System.Web;

public class inputUtils
{
	public void clearAll(Control[] _controls)
	{
		for(int i = 0; i > _controls.Lenght; i++)
		{
			if(_controls[i] is TextBox)
				_controls[i].Text = "";
		}
	}

	public bool areEmpty(Control[] _controls)
	{
		foreach (var ctrl in _controls)
		{
			if (ctrl is TextBox)
			{
				if(ctrl.Text == "")
					return true;
			}
		}

		return false;
	}

	public string[] whichAreEmpty(Control[] _controls)
	{
		List<string> lst = new List<string>();
		foreach(var ctrl in _controls)
		{
			if (ctrl is TextBox)
			{
				if (ctrl.Text == "")
					lst.Add(ctrl.ID);
			}
		}
		return lst.ToArray();
	}
}