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3. Custom formatting
spdlog's default logging format is in the form of:
[2014-31-10 23:46:59.678] [info] [my_loggername] Some message
There are 2 ways to customize log format:
- Use
logger.set_pattern(std::string pattern_string)(recommended) - Or implement custom formatter that implements the formatter interface
and call
set_formatter(std::make_shared<my_custom_formatter>())
Format can be applied globally to all loggers:
spdlog::set_pattern("*** [%H:%M:%S %z] [thread %t] %v ***");
or to a specific logger object:
some_logger.set_pattern(">>>>>>>>> %H:%M:%S %z %v <<<<<<<<<");
Whenever the user calls set_pattern("..") the library "compiles" the new pattern to an internal efficient representation - This way the performance stays excellent even with complex patterns (no re-parsing of the pattern on each log call).
Pattern flags are in the form of %[flag] and resembles [strftime] (http://www.cplusplus.com/reference/ctime/strftime/) function.. Anything that is not pattern flag will be logged as is..
|flag|meaning|example| |-------|:-------:|:-----:|------:| |%v|The actual text to log|"some user text"| |%t|Thread id|"1232"| |%n|Logger's name|"some logger name" |%l|The log level of the message|"debug", "info", etc| |%L|Short log level of the message|"D", "I", etc| |%a|Abbreviated weekday name|"Thu"| |%A|Full weekday name|"Thursday"| |%b|Abbreviated month name|"Aug"| |%B|Full month name|"August"| |%c|Date and time representation|"Thu Aug 23 15:35:46 2014"| |%C|Year in 2 digits|"14"| |%Y|Year in 4 digits|"2014"| |%D or %x|Short MM/DD/YY date|"08/23/14"| |%m|Month 1-12|"11"| |%d|Day of month 1-31|"29"| |%H|Hours in 24 format 0-23|"23"| |%I|Hours in 12 format 1-12|"11"| |%M|Minutes 0-59|"59"| |%S|Seconds 0-59|"58"| |%e|Millisecond part of the current second 0-999|"678"| |%f|Microsecond part of the current second 0-999999|"056789"| |%F|Nanosecond part of the current second 0-999999999|"256789123"| |%p|AM/PM|"AM"| |%r|12 hour clock|"02:55:02 pm"| |%R|24-hour HH:MM time, equivalent to %H:%M|"23:55"| |%T or %X|ISO 8601 time format (HH:MM:SS), equivalent to %H:%M:%S|"23:55:59"| |%z|ISO 8601 offset from UTC in timezone ([+/-]HH:MM)|"+02:00"| |%%|The % sign|"%"| |%+|spdlog's default format|"[2014-31-10 23:46:59.678] [info] [mylogger] Some message"