How to create functions like std::cout?

Question

I\'m creating my own logging utility for my project, I want to create a function like iostream\'s std::cout, to log to a file and print to the console as well.

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Answer 1

std::cout is not a function, it's an object of type std::ostream which overloads operator<<.

A quick sketch of how you could do it:

enum Level {
    debug, error, warning, info
};

struct Logger {
    std::ostream* stream;  // set this in a constructor to point
                           // either to a file or console stream
    Level debug_level;
public:
    Logger& operator<<(const std::string& msg)
    {
        *stream << msg; // also print the level etc.
        return *this;
    }

    friend Logger& log(Logger& logger, Level n);
    {
        logger.debug_level = n;
        return logger;
    }
};

Ant then use it like

Logger l;
log(l, debug) << "test";