var errormsg="";
function checkEmail(email,name)
{
   var at1      =  email.indexOf("@");
   var at2      =  email.lastIndexOf("@");
   var dot     =  email.lastIndexOf(".");
   var space   =  email.indexOf(" ");
   if((at1!=-1)&&
      (at1!=0)&&
      (at2==at1)&&
      (dot!=-1)&&
      (dot>at1+1)&&
      (dot<email.length-1)&&
      (space==-1))
   {
      return true;
   }
   else
   {
      errormsg=errormsg+name+"\n";
      return false;
   }
}
function checkTextField(str,name)
{
	if(str=="")
	{
		errormsg=errormsg+name+'\n';
		return false;
	}
	else
		return true;
}
function checkPassword(p,namep,rp,namerp)
{
	if(p!=="")
	{
		if(p==rp)
	 		return true;
	 	else
		{
			errormsg=errormsg+namep+namerp;
			return false;
		}
	}
	else
	{
		checkTextField(p,namep);
		return false;
	}
}
function checkIsIntNum(val,name)
{
	if((val!="")&&(!isNaN(val)) && val.indexOf(".")<0)
		return true;
	else
	{
		errormsg=errormsg+"- "+name+" khong phai la so nguyen.<br>";
		return false;
	}
}
function checkIsNum(val,name)
{
	if((val!="")&&(!isNaN(val)))
		return true;
	else
	{
		errormsg=errormsg+"- "+name+" khong phai la mot so.<br>";
	}

}
function checkAll()
{
	if(errormsg!="")
	{
		alert(errormsg);
		errormsg="";
		return false;
	}
	else
		return true;
	errormsg="";
}
function setCheckboxes(the_form, the_box, do_check)
{
    var elts      = (typeof(document.forms[the_form].elements[the_box]) != 'undefined')
                  ? document.forms[the_form].elements[the_box]
                  : document.forms[the_form].elements[the_box];
    var elts_cnt  = (typeof(elts.length) != 'undefined')
                  ? elts.length
                  : 0;

    if (elts_cnt) {
        for (var i = 0; i < elts_cnt; i++) {
            elts[i].checked = do_check;
        }
    } else {
        elts.checked        = do_check;
    }
    return true;
}

function checkCheckboxes(the_form, the_box)
{
   var elts      = (typeof(document.forms[the_form].elements[the_box]) != 'undefined')
                  ? document.forms[the_form].elements[the_box]
                  : document.forms[the_form].elements[the_box];
   var elts_cnt  = (typeof(elts.length) != 'undefined')
                  ? elts.length
                  : 0;
	err=false;

	if (elts_cnt)
   {
		for (var i = 0; i < elts_cnt; i++)
		{
			if(elts[i].checked == true)
			{
				err=true;
				break;
			}
		}

	}
	else if(document.forms[the_form].elements[the_box].checked==true)
	{
		err=true;
	}

	return err;
}
function checkSelections(the_form, the_box)
{
   var elts      = (typeof(document.forms[the_form].elements[the_box]) != 'undefined')
                  ? document.forms[the_form].elements[the_box]
                  : document.forms[the_form].elements[the_box];
   var elts_cnt  = (typeof(elts.length) != 'undefined')
                  ? elts.length
                  : 0;
	err=false;

	if (elts_cnt)
   {
		for (var i = 0; i < elts_cnt; i++)
		{
			if(elts[i].selected == true)
			{
				err=true;
				break;
			}
		}

	}
	else if(document.forms[the_form].elements[the_box].selected==true)
	{
		err=true;
	}

	return err;
}