请问以下代码中ss<<的 用法是什么意思啊? 谢谢!
stringstream ss;
ss << "insert into list (id, name, username, idcard, price, count) values(";
ss << "'" << id << "',";
ss << "'" << name << "',";
ss << "'" << username << "',";
ss << "'" << idcard << "',";
ss << price << ",";
ss << count << ");";