将Cout从C ++中的各种来源重定向到同一文件 [英] Redirecting cout into same file from various sources in c++

问题描述

我的问题是我在项目的各个文件中都有几个cout.我希望将它们全部重定向并保存在 .txt 文件中，到目前为止，我所实现的是在文件中仅保存了一个cout.我不想为每个 cout 创建单独的 .txt ，以便一次阅读它们.我的代码现在看起来像这样:

my problem is I have a couple of cout's in various files in the project. I would like all of them to be redirected and saved in .txt file, and what I achieved by now is that only one cout is saved in the file. I don't want to create separate .txt for each cout, for the sake of reading them at once. My code looks now like this:

#include <fstream>
#include <string>
#include <iostream>

int main()
{
    std::ofstream out("out.txt");
    std::cout.rdbuf(out.rdbuf()); 

    std::cout << "get it3";
    std::cout << "get it4"; 
}

两个 cout 都在一个文件中，但是假设它们在两个不同的文件中，如何重定向并保存在一个 .txt 中?

Both cout are in one file, but assuming they are in two different, how to redirect and save in one .txt?

推荐答案

显而易见的答案是，您永远不要输出到 std :: cout .所有实际输出应为 std :: ostream& ，默认情况下可以将其设置为 std :: cout ，但是您可以初始化为其他东西.

The obvious answer is that you should never output to std::cout. All actual output should be to an std::ostream&, which may be set to std::cout by default, but which you can initialize to other things as well.

另一个明显的答案是重定向应该在开始该过程.

Another obvious answer is that redirection should be done before starting the process.

但是，假设您不能更改输出的代码到 std :: cout ，并且您无法控制对您的程序(或者您只想更改某些输出)，您可以通过附加来更改 std :: cout 本身的输出一个不同的 streambuf .在这种情况下，我也会使用RAII确保当您退出时， std :: cout 具有流缓冲功能期望.但类似以下内容的方法应该起作用:

Supposing, however, that you cannot change the code outputting to std::cout, and that you cannot control the invocation of your program (or you only want to change some of the outputs), you can change the output of std::cout itself by attaching a different streambuf. In this case, I'd use RAII as well, to ensure that when you exit, std::cout has the streambuf it expects. But something like the following should work:

class TemporaryFilebuf : public std::filebuf
{
    std::ostream&   myStream;
    std::streambuf* mySavedStreambuf;
public:
    TemporaryFilebuf(
            std::ostream& toBeChanged,
            std::string const& filename )
        : std::filebuf( filename.c_str(), std::ios_base::out )
        , myStream( toBeChanged )
        , mySavedStreambuf( toBeChanged.rdbuf() )
    {
        toBeChanged.rdbuf( this );
    }
    ~TemporaryFilebuf()
    {
        myStream.rdbuf( mySavedStreambuf );
    }
};

(您可能要添加一些错误处理；例如，如果您无法打开文件.)

(You'll probably want to add some error handling; e.g. if you cannot open the file.)

当您输入要重定向输出的区域时，只需使用流( std :: cout 或其他任何方法)创建一个实例 ostream )和文件名.当实例是销毁后，输出流将恢复输出到无论以前输出到哪里.

When you enter the zone where you wish to redirect output, just create an instance with the stream (std::cout, or any other ostream) and the name of the file. When the instance is destructed, the output stream will resume outputting to whereever it was outputting before.

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