extern ostream clog;

Standard output stream for logging

clog is an object of class ostream that represents the standard logging stream. It is associated with the cstdio stream stderr, like cerr.

By default, most systems have their standard error and logging output directed to the console, where text messages are shown, although this can generally be redirected.

Because clog is an object of class ostream, we can write characters to it either as formatted data using for example the insertion operator (ostream::operator<<) or as unformatted data using the write member function, among others (see ostream).

See also