function validaCampos()
{
	// txt_email
	if (document.enviaDados.txt_email.value == "")
		  {
		  window.alert("Por favor digite o campo e-mail.");
		  document.enviaDados.txt_email.focus();
		  return false;
		  }

		var checkcliEmail = "@.";
		var checkStr = document.enviaDados.txt_email.value;
		var cliEmailValid = false;
		var cliEmailAt = false;
		var cliEmailPeriod = false;

		for (i = 0;  i < checkStr.length;  i++)
			{
			ch = checkStr.charAt(i);

			for (j = 0;  j < checkcliEmail.length;  j++)
				{

				if (ch == checkcliEmail.charAt(j) && ch == "@")
				cliEmailAt = true;

				if (ch == checkcliEmail.charAt(j) && ch == ".")
				cliEmailPeriod = true;

				if (cliEmailAt && cliEmailPeriod)
				break;

				if (j == checkcliEmail.length)
				break;
			 	}

			if (cliEmailAt && cliEmailPeriod)
				{
				cliEmailValid = true
				break;
			}
			}

		if (!cliEmailValid)
			{
			window.alert("Por favor digite um e-mail válido.");
			document.enviaDados.txt_email.focus();
			return false;
			}

	  // enviar dados
      else
        {
        document.enviaDados.submit();
        }
}

// input só aceita número
function soNumero(e)
         {
         var key //= (window.event) ? event.keyCode : e.which;
         if (window.event)
             key = event.keyCode
         else
             key = e.which
             // Was key that was pressed a numeric character (0-9) or backspace (8)?
           if (key > 47 && key < 58 || key == 8 || key == 0)
               return; // if so, do nothing
           else // otherwise, discard character

           if (window.event) //IE
               window.event.returnValue = null;
           else //Firefox
               e.preventDefault();
}

// checar se são números
var oldvalue = [''];

function verifyNumeric(which)
{
if (isNaN(which.value))
{
if (oldvalue[which])
{
which.value = oldvalue[which];
}
else
{
which.value = '';
oldvalue[which] = '';
}
}
else
{
oldvalue[which] = which.value;
}
}