问题

I'm new to C++ and not 100% sure how I can iterate over maps. For the project, I need to have a map that stores key: [name of file / stream] and value: [logger::severity]. Among the filenames there might be an object of ostream cout.

我是C++的新手，不太确定如何遍历映射。在这个项目中，我需要一个映射，它将键：[文件名/流的名称] 和 值：[logger::severity] 存储在其中。在文件名中可能会有一个 ostream cout 对象。

I came up to pretty much nothing:

我几乎一无所获：

enum class severity
{
    trace,
    debug,
    information,
    warning,
    error,
    critical
};

std::map<std::ofstream, severity> this_loggers_streams;

for (std::map<std::ofstream, severity>::iterator iter = this_loggers_streams.begin(); 
      iter != this_loggers_streams.end(); ++iter) {
  iter->first << "" << std::endl;      
  }
}

My IDE warns me that there is a no viable conversion for my iterator and Invalid operands to binary expression (const std::basic_ofstream<char> and const char[1]).

我的集成开发环境警告我，我的迭代器没有合适的转换，以及二进制表达式的操作数无效（const std::basic_ofstream<char> 和 const char[1]）。

How can I iterate over my map? What will be the best solution to have an ability to write in a file and in std::cout as it can be a member of my map?

我该如何遍历我的映射？如何最好地实现在文件和std::cout中写入数据，因为它可能是我的映射的成员之一？

enum class severity
    {
        trace,
        debug,
        information,
        warning,
        error,
        critical
    };

std::map<std::ofstream, severity> this_loggers_streams;

for (std::map<std::ofstream, severity>::iterator iter = this_loggers_streams.begin(); 
          iter != this_loggers_streams.end(); ++iter) {
      iter->first << "" << std::endl;      
      }
}

答案1

得分: -1

地图中的键是常量值。那段代码是无效的，如果不改变软件设计，就无法修复：

iter->first << "" << std::endl;  // iter->first 是 const std::ofstream

一个可能的更改：

std::list<std::pair<std::ofstream, severity>> this_loggers_streams;

iter->first << "" << std::endl;  // iter->first is const std::ofstream

std::list<std::pair<std::ofstream, severity>> this_loggers_streams;