How to override cout in C++?

Question

I have a requirement, I need to use printf and cout to display the data into console and file as well. For printf I have

Answer 1

I assume you have some code using std::cout and printf which you cannot modify, otherwise the most simple way to solve your problem would be to write to a different stream from cout and use fprintf rather than or in conjunction with printf.

By following that approach you could define both a new stream class that actually wrote both to standard output and to a given file, as well as a function that combined calls to both printf and fprintf.

However a much simpler approach is to use the tee program, originally from UNIX, which copies its input both to output and to a given file. With that you could simply call your program in this way:

your_program | tee your_log_file

Answers to this question lead to a few alternative implementations available for Windows. Personally I always install cygwin on my PC's to have UNIX/Linux utilities available.