std::clog, std::wclog

The global objects std::clog and std::wclog control output to a stream buffer of implementation-defined type (derived from std::streambuf), associated with the standard C output stream stderr, but, unlike std::cerr/std::wcerr

These objects are guaranteed to be initialized during or before the first time an object of type std::ios_base::Init is constructed and are available for use in the constructors and destructors of static objects with ordered initialization (as long as <iostream>

Unless std:: ios_base :: sync_with_stdio ( false )

Notes

The 'c' in the name refers to "character" (stroustrup.com FAQ); clog means "character log" and wclog

Example

#include <iostream>
 
struct Foo
{
    int n;
    Foo()
    {
        std::clog << "static constructor\n";
    }
    ~Foo()
    {
        std::clog << "static destructor\n";
    }
};
 
Foo f; // static object
 
int main()
{
    std::clog << "main function\n";
}

static constructor
main function
static destructor

See also