function is_string_num(str) {
	for(var i = 0; i < str.length; i++) {
		var ch = str.substring(i, i + 1)
		if(ch < "0" || ch > "9")
			return false;
	}
	return true;
}

function is_char_num(charCode) {
    if (charCode > 31 && (charCode < 48 || charCode > 57)) {
        return false;
    }
    return true;
}

function is_email(ele) {
	var al = "email invalid";
	var str = ele.value;
	var filter = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i;
	if (filter.test(str))
		return true;
	else {
		alert(al);
		return false
	}
}

function has_control_char(ele) {
	var al = "do not use & ' \" + - ";
	var str = ele.value;
	
	if(str.indexOf("&") == -1 && str.indexOf("'") == -1 && str.indexOf("\"") == -1 && str.indexOf("+") == -1  && str.indexOf("-") == -1) {
		return false;
	}
	else {
		alert(al);
		return true;
	}
}

function isEnglish(ele) {
	var str = ele.value;
	var len, digit;
	len = str.length;
	
	for(var i=0 ; i<len ; i++) {
		digit = str.charAt(i);
		
		if(((digit >= "a" && digit <= "z") || (digit >= "0" && digit <= "9") || (digit >= "A" && digit <= "Z")) || (digit == "_")) {
			;
		} else
			return false;
	} 
	return true;
}