string去除指定字符

啥也不说，就是好用，代码很简单，不解释!

	string deleteAllMarks(string& str, const string& mark){
		size_t len = mark.length();
		while (1){
			size_t pos = str.find(mark);
			if (pos == string::npos){
				return str;
			}
			str.erase(pos, len);
		}
	}