function isRightString(s){
	var c;
	for(var i = 0; i < s.length; i++){
		c = s.substr(i, 1);
		if(!(isChar(c)) && !(isNumber(c)) && (c != '_') && (c != '-') && (c != '.') && (c != "@")){
			return false;
		}  
	}
	return true;
}

function isChar(c){
	if(((c >= 'a')&&(c <= 'z')) || ((c >= 'A')&&(c <= 'Z'))){
		return true;
	}else{
		return false;
	}
}

function isNumber(c){
	if((c >= '0')&&(c <= '9')){
		return true;
	}else{
		return false;
	}
}

function isRightStr4Email(email){
	if(email.length <= 8){
		return false;
	}
	if(!isRightString(email)){
		return false;
	}
	if(email.indexOf("@") == -1 || email.indexOf("@") == 0){
		return false;
	}
	if(email.lastIndexOf("@") >= (email.length - 4)){
		return false;
	}
	if(email.indexOf(".") == -1 || email.indexOf(".") == 0){
		return false;
	}
	if(email.lastIndexOf(".") >= (email.length - 2)){
		return false;
	}
	if(email.substring(email.indexOf("@"),email.length).indexOf(".") == -1){
		return false;
	}
	if(email.substring(email.indexOf("@")+1,(email.indexOf("@")+2)) == "."){
		return false;
	}
	
	var ch;
	var j = 0;
	for(var i = 0; i < email.length; i++){
		ch = email.substr(i,1);
		if(ch == "@"){
			j++;
		}  
	}
	if(j != 1){
		return false;
	}

	return true;
}