将std :: cout的副本重定向到该文件

Question

我需要将std :: cout 的副本重定向到该文件.即我需要在控制台和文件中看到输出.如果我用这个:

// redirecting cout's output
#include <iostream>
#include <fstream>
using namespace std;

int main () {
  streambuf *psbuf, *backup;
  ofstream filestr;
  filestr.open ("c:\\temp\\test.txt");

  backup = cout.rdbuf();     // back up cout's streambuf

  psbuf = filestr.rdbuf();   // get file's streambuf
  cout.rdbuf(psbuf);         // assign streambuf to cout

  cout << "This is written to the file";

  cout.rdbuf(backup);        // restore cout's original streambuf

  filestr.close();

  return 0;
}

然后我将字符串写入文件,但我在控制台中看不到任何内容.我该怎么做？

Answer 1

您可以做的最简单的事情是创建一个输出流类来执行此操作:

#include <iostream>
#include <fstream>

class my_ostream
{
public:
  my_ostream() : my_fstream("some_file.txt") {}; // check if opening file succeeded!!
  // for regular output of variables and stuff
  template<typename T> my_ostream& operator<<(const T& something)
  {
    std::cout << something;
    my_fstream << something;
    return *this;
  }
  // for manipulators like std::endl
  typedef std::ostream& (*stream_function)(std::ostream&);
  my_ostream& operator<<(stream_function func)
  {
    func(std::cout);
    func(my_fstream);
    return *this;
  }
private:
  std::ofstream my_fstream;
};

请参阅此ideone链接以了解此代码的运行情况:http://ideone.com/T5Cy1M 我目前无法检查文件输出是否正确完成,尽管它应该不是问题.