Redirecting output to files for specific code sections
The std::cout provides a really nice way to print whatever we want, whenever we want because it is simple to use, easily extensible, and globally accessible. Even if we want to print special messages, such as error messages, which we want to isolate from normal messages, we can just use std::cerr, which is the same as cout but prints to the standard error channel instead of the standard output channel.
We might have some more complicated desires for logging sometimes. Let's say, for example, we want to redirect the output of a function to a file, or we want to mute the output of a function, without changing the function at all. Perhaps, it is a library function we cannot access the source code of. Maybe, it was never designed to write to a file but we want its output in a file.
It is indeed possible to redirect the output of stream objects. In this recipe, we are going to see how to do that in a very simple and elegant way.
