std::clog, std::wclog
From cppreference.com
| Defined in header
<iostream>
|
||
| extern std::ostream clog;
|
(1) | |
| extern std::wostream wclog;
|
(2) | |
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 streams are not automatically flushed and not automatically tie()'d with cout.
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 (as long as <iostream> is included).
Unless sync_with_stdio(false) has been issued, it is safe to concurrently access these objects from multiple threads for both formatted and unformatted output.
[edit] Example
Run this code
#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"; }
Output:
static constructor main function static destructor
[edit] See also
| initializes standard stream objects (public member class of std::ios_base)
|
|
| writes to the standard C error stream stderr, unbuffered (global object) |
|
| writes to the standard C output stream stdout (global object) |