For application output we use Logog which is already integrated in OGS. Logog provides several verbosity levels which can be used with simple macro calls:
As arguments you can use the same functionality as in sprintf:
For more information see the Logog documentation.
On release builds the log level is
LOGOG_LEVEL_INFO, on debug it is
LOGOG_LEVEL_DEBUG and it can be overriden with the CMake option
OGS_LOG_LEVEL. You can completely disable logging with the CMake-option
OGS_DISABLE_LOGGING set to