function isValidUsername(str)
{	
	for(i=0; i<str.length;i++)
	{	if( ((str.charCodeAt(i)>=97) && (str.charCodeAt(i)<123)) ||
			((str.charCodeAt(i)>=48) && (str.charCodeAt(i)<=57)) ||
			(str.charAt(i)=="_")								 ||
			(str.charCodeAt(i)>256 || str.charCodeAt(i)<0)
		  )
		{;}
		else
		{return false;}
	}
	return true;
}

// 范围的确定 isBetween(val, lo, hi)
// 返回值：在指定范围内为 true, 否则为 false
function isBetween (val, lo, hi) {
	if ((val < lo) || (val > hi)) { return (false); }
	else { return (true); }
}

// 日期的确认 isDate()
// 返回值：正确 true, 错误 false
function isDate (theStr) {
	var the1st = theStr.indexOf ('/');
	var the2nd = theStr.lastIndexOf ('/');
	if (the1st == the2nd) { return (false); }
	else {
		var m = theStr.substring (0, the1st);
		var d = theStr.substring (the1st + 1, the2nd);
		var y = theStr.substring(the2nd + 1, theStr.length);
		var maxDays = 31;
		if (isInt (m) == false || isInt (d) == false || isInt (y) == false) {
			return (false);
		}
		else if (y.length < 4) { return (false); }
		else if (!isBetween ( m, 1, 12)) { return (false); }
		else if (m == 4 || m == 6 || m == 9 || m == 11) maxDays = 30;
		else if (m == 2) {
			if ( y % 4 > 0) maxDays = 28;
			else if ( y % 100 == 0 && y % 400 > 0) maxDays = 28;
			else maxDays = 29;
		}
		if (isBetween (d, 1, maxDays) == false) { return (false); }
		else { return (true); }
	}
}

// 时间确认 isTime()
// 返回值：正确 true, 错误 false
function isTime (theStr) {
	var colonDex = theStr.indexOf (':');
	if ((colonDex < 1) || (colonDex > 2)) { return (false); }
	else {
		var hh = theStr.substring (0, colonDex);
		var ss = theStr.substring (colonDex + 1, theStr.length);
		if (( hh.length < 1) || ( hh.length > 2) || (!isInt(hh))) { return (false); }
		else if ((ss.length < 1) || (ss.length > 2) || (!isInt(ss))) { return (false); }
		else if ((!isBetween (hh, 0, 23)) || (!isBetween (ss, 0, 59))) { return (false); }
		else { return (true); }
	}
}

// 数字确认 isDigit(theNum)
// 返回值：正确 true, 错误 false
function isDigit (theNum) {
	var theMask = '0123456789';
	if (isEmpty (theNum)) return (false);
	else if (theMask.indexOf (theNum) == -1) return (false);
	return (true);
}

// 电子邮件地址格式确认 isEmail(theStr)
// 返回值：格式正确 true, 格式错误 false
function isEmail (theStr) {
	var atIndex = theStr.indexOf ('@');
	var dotIndex = theStr.indexOf ('.', atIndex);
	var flag = true;
	var theSub = theStr.substring (0, dotIndex + 1);
	if ((atIndex < 1) || (atIndex != theStr.lastIndexOf ('@')) || (dotIndex < atIndex + 2) || (theStr.length <= theSub.length))
	{
		flag = false;
	}
	else { flag = true; }
	return (flag);
}

// 检查输入是否为空 isEmpty(str)
// 参数：
//    str: 密码字符串；
//    minLength: 密码的最小长度
// 返回值：空 true, 非空 false
function isEmpty (str, minLength) {
	if (str.length < minLength) return true;
	else return (false);
}

// 检查输入是否为整数 isInt(theStr)
// 返回值：整数 true, 非整数 false
function isInt (theStr) {
	var flag = true;
	if (isEmpty (theStr)) { flag = false; }
	else 
	{
		for (var i = 0; i < theStr.length; i++) {
			if (isDigit (theStr.substring (i, i + 1)) == false) {
				flag = false; break;
			}
		}
	}
	return (flag);
}

// 检查输入是否为实数 isReal(theStr, decLen)
// 返回值：实数 true, 非实数 false
function isReal (theStr, decLen) {
	var dot1st = theStr.indexOf ('.');
	var dot2nd = theStr.lastIndexOf ('.');
	var OK = true;
	if (isEmpty (theStr)) return false;
	if (dot1st == -1){
		if (!isInt (theStr)) return (false);
		else return (true);
	}
	else if (dot1st != dot2nd) return (false);
	else if (dot1st == 0) return (false);
	else {
		var intPart = theStr.substring (0, dot1st);
		var decPart = theStr.substring (dot2nd + 1);
		if (decPart.length > decLen) return (false);
		else if (!isInt (intPart) || !isInt (decPart)) return (false);
		else if (isEmpty (decPart)) return (false);
		else return (true);
	}
}

function checkchinese(theelement)
{//如果含有中文字符返回 true
   text="abcdefghijklmnopqrstuvwxyz1234567890 ABCDEFGHIJKLMNOPQRSTUVWXYZ,/()!@$%&\#*~.;'_-";
   for(i=0;i<=theelement.length-1;i++)
   {
      char1=theelement.charAt(i);
      index=text.indexOf(char1);
      if(index==-1)
      {
         return true;//有中文
      }  
     //没有中文
   }
   return false;
}