Creating fstream object from a FILE* pointer

c++ popen ifstream
Tabrez Ahmed picture Tabrez Ahmed · May 19, 2012 · Viewed 13.2k times · Source

The well known way of creating an fstream object is:

ifstream fobj("myfile.txt");

ie. using a filename.

But I want to create an ifstream object using a file descriptor.

Reason: I want to execute a command using _popen(). _popen() returns the output as a FILE*. So there is a FILE* pointer involved but no filename.

Answer

Kerrek SB picture Kerrek SB · May 19, 2012

You cannot do that just in standard C++, since iostreams and C I/O are entirely separate and unrelated. You could however write your own iostream that's backed by a C FILE stream. I believe that GCC comes with one such stream class as a library extension.

Alternatively, if all you want is an object-y way of wrapping a C FILE stream, you could use a unique pointer for that purpose.

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