EasyLogging++

Cross platform logging made easy for C++ applications.

To use EasyLogging++ in your application, simply:

#include "easylogging++.h"

EasyLogging++ comes with following levels of logging with complete control over each of the following:

  DEBUG(...)
  INFO(...)
  WARN(...)
  ERROR(...)
  FATAL(...)
  PERFORMANCE(...)
  HINT(...)
  STATUS(...)

Examples

Basic Logging

#include "easylogging++.h"
int main(void) {
   DEBUG("Staring my EasyLogging++ program");
   unsigned int i = 0;
   INFO("Current value is " << i);
   INFO("Now the value has changed from " << i++ << " to " << i);
   DEBUG("End of my EasyLogging++ program");
}

Output with no extra info

[DEBUG] Staring my EasyLogging++ program
[INFO] Current value is 0
[INFO] Now the value has changed from 0 to 1
[DEBUG] End of my EasyLogging++ program

Output with `SHOW_LOG_LOCATION` but `SHOW_TIME`, `SHOW_DATE` and `SHOW_LOG_FUNCTION`, `SHOW_USERNAME` and `SHOW_HOSTNAME` set to false

[DEBUG] [/home/easyloggertest/main.cpp:3]
    Staring my EasyLogging++ program
[INFO] [/home/easyloggertest/main.cpp:5]
    Current value is 0
[INFO] [/home/easyloggertest/main.cpp:6]
    Now the value has changed from 0 to 1
[DEBUG] [/home/easyloggertest/main.cpp:7]
    End of my EasyLogging++ program

Output with `SHOW_TIME`, `SHOW_LOG_LOCATION` but `SHOW_DATE` and `SHOW_LOG_FUNCTION`, `SHOW_USERNAME` and `SHOW_HOSTNAME` set to false

[DEBUG] [14:34:38] [/home/easyloggertest/main.cpp:3]
    Staring my EasyLogging++ program
[INFO] [14:34:38] [/home/easyloggertest/main.cpp:5]
    Current value is 0
[INFO] [14:34:38] [/home/easyloggertest/main.cpp:6]
    Now the value has changed from 0 to 1
[DEBUG] [14:34:38] [/home/easyloggertest/main.cpp:7]
    End of my EasyLogging++ program

Output with `SHOW_DATE`, `SHOW_TIME`, `SHOW_LOG_LOCATION` and `SHOW_LOG_FUNCTION` but `SHOW_USERNAME` and `SHOW_HOSTNAME` set to false

[DEBUG] [Sep 23 2012 14:34:38] [int main(int,char**)] [/home/easyloggertest/main.cpp:3]
    Staring my EasyLogging++ program
[INFO] [Sep 23 2012 14:34:38] [int main(int,char**)] [/home/easyloggertest/main.cpp:5]
    Current value is 0
[INFO] [Sep 23 2012 14:34:38] [int main(int,char**)] [/home/easyloggertest/main.cpp:6]
    Now the value has changed from 0 to 1
[DEBUG] [Sep 23 2012 14:34:38] [int main(int,char**)] [/home/easyloggertest/main.cpp:7]
    End of my EasyLogging++ program

Note: SHOW_LOG_FUNCTION depends on compiler and is supported by Visual C++ and GNU C >= 2 only

Performance Logging

#include "easylogging++.h"
SUB(print,(const std::string& input))
  /* sub-routine body */
  std::cout << input;
END_SUB 

FUNC(int,sum,(int x,int y))
  /* function body */
  RETURN(x+y);
END_FUNC 

int main(void) {
   print("this is test");
   int sumResult = sum(1,2);
   std::cout << "Sum of 1 and 2 is " << sumResult;
}

Output

this is test
[PERFORMANCE] Executed [void print(string)] in [~0 seconds]
[PERFORMANCE] Executed [int sum(int, int)] in [~0 seconds]
Sum of 1 and 2 is 3

Please note, the function name information varies from compiler to compiler. Some support the whole signature (that is very useful in case of overloaded functions) while others support just function name. This gets hard at times when we have overloaded function or two classes (or namespace) having same function name. But in this kind of situation, EasyLogging++'s SHOW_LOG_LOCATION configuration is very useful that you will see in coming section Configuration.

Above output is from compiler that supports PRETTY_FUNCTION like GNU C >= 2. Visual C++ will output just the function name i.e, print and sum in this case.

Some Notes on Performance Logging

Make sure you have braces around RETURN

   if (condition) {
      RETURN(0);
   }

To exit a subroutine, do not call return; instead, use RETURN()

  if (condition) {
     RETURN();
  }

Use normal definition syntax for other types of functions

inline FUNC(int,sqrt,(int numb))
   ...
END_FUNC

template <typename T>
static FUNC(T,sum,(T a,T b))
   ...
END_FUNC

Note: you have many other configurations to change your output. See following section for details

Configuration

Enable/Disable Logging

By Default logging is enabled and you can use it in your aplication. There are few things that you might want to configure.

_LOGGING_ENABLED macro enables or disables logging (0 for disable 1 for enable)
_ENABLE_DEBUG_LOGS macro enables or disables debugging logs (0 for disable 1 for enable)
_ENABLE_INFO_LOGS macro enables or disables info logs (0 for disable 1 for enable)
_ENABLE_WARNING_LOGS macro enables or disables warning logs (0 for disable 1 for enable)
_ENABLE_ERROR_LOGS macro enables or disables error logs (0 for disable 1 for enable)
_ENABLE_FATAL_LOGS macro enables or disables fatal logs (0 for disable 1 for enable)
_ENABLE_PERFORMANCE_LOGS macro enables or disables performance logs (0 for disable 1 for enable)
_ENABLE_HINTS macro enables or disables hints (0 for disable 1 for enable)
_ENABLE_STATUS macro enables or disables status logs (0 for disable 1 for enable)

Note, when the logging is turned off, it will not affect any code, it will not result in any compilation error, in fact, compiler will ignore those lines. Even the functions defined using SUB and FUNC will behave normally as they would do otherwise when EasyLogging++ is not being used at all.

Log Location By Log Level

Since v2.0+, EasyLogging++ has configuration for custom log locations, that means; for example you can choose to log DEBUGs to log file but not to standard output (e.g, terminal) while INFO to both standard output and log file. This can be set by following configurations

_DEBUG_LOGS_TO_STANDARD_OUTPUT to enable/disable debug logs to be shown in standard output (0 for disable 1 for enable)
_DEBUG_LOGS_TO_FILE to enable/disable saving debug logs to log file (0 for disable 1 for enable)
_INFO_LOGS_TO_STANDARD_OUTPUT to enable/disable info logs to be shown in standard output (0 for disable 1 for enable)
_INFO_LOGS_TO_FILE to enable/disable saving info logs to log file (0 for disable 1 for enable)
_WARNING_LOGS_TO_STANDARD_OUTPUT to enable/disable warning logs to be shown in standard output (0 for disable 1 for enable)
_WARNING_LOGS_TO_FILE to enable/disable saving debug warning to log file (0 for disable 1 for enable)
_ERROR_LOGS_TO_STANDARD_OUTPUT to enable/disable error logs to be shown in standard output (0 for disable 1 for enable)
_ERROR_LOGS_TO_FILE to enable/disable saving error logs to log file (0 for disable 1 for enable)
_FATAL_LOGS_TO_STANDARD_OUTPUT to enable/disable fatal logs to be shown in standard output (0 for disable 1 for enable)
_FATAL_LOGS_TO_FILE to enable/disable saving fatal logs to log file (0 for disable 1 for enable)
_PERFORMANCE_LOGS_TO_STANDARD_OUTPUT to enable/disable performance logs to be shown in standard output (0 for disable 1 for enable)
_PERFORMANCE_LOGS_TO_FILE to enable/disable saving performance logs to log file (0 for disable 1 for enable)
_HINTS_TO_STANDARD_OUTPUT to enable/disable hints to be shown in standard output (0 for disable 1 for enable)
_HINTS_TO_FILE to enable/disable saving hints to log file (0 for disable 1 for enable)
_STATUS_TO_STANDARD_OUTPUT to enable/disable status logs to be shown in standard output (0 for disable 1 for enable)
_STATUS_TO_FILE to enable/disable saving status logs to log file (0 for disable 1 for enable)

Other Configurations

/**
* Flag for showing log in standard output using std::cout
*/
const bool SHOW_STD_OUTPUT = true;

/**
* Flag to set whether to save log to file
*/
const bool SAVE_TO_FILE = true;

/**
* Flag to set whether to show date
*/
const bool SHOW_DATE = false;

/**
* Flag to set whether to show time
*/
const bool SHOW_TIME = true;

/**
* Flag to set whether to show which file logged the output and what line
*/
const bool SHOW_LOG_LOCATION = true;

/**
* Flag to set whether to show which function logged the output and what line
*/
const bool SHOW_LOG_FUNCTION = true;

/**
* Flag to set whether to show username or not
*/
const bool SHOW_USERNAME = true;

/**
* Flag to set whether to show hostname or not
*/
const bool SHOW_HOSTNAME = true;

/**
* Flag to set whether output value of NOT_SUPPORTED_STRING if extra info is not available on machine
*/
const bool SHOW_NOT_SUPPORTED_ON_NO_EXTRA_INFO = false;

/**
* outputs if extra info is not available on machine and SHOW_NOT_SUPPORTED_ON_NO_EXTRA_INFO is true
*/
const std::string NOT_SUPPORTED_STRING = "-not supported-";

/**
* If saving to file, this defines the filename
*/
const std::string LOG_FILENAME = "myeasylog.log";

/**
* Flag to set whether to save log file in custom location
*/
const bool USE_CUSTOM_LOCATION = false;

/**
* If using custom location, this is where custom location is picked up from.
* Note: This should end with last slash 
*/
const std::string CUSTOM_LOG_FILE_LOCATION = "";

/**
 * Determines whether to show log when starting any time tracked function
 */
const bool SHOW_START_FUNCTION_LOG = true;

LICENCE

This program is free software: you can redistribute it and/or modify it under the terms of the 
GNU General Public License as published by the Free Software Foundation, version 3 of the License.

vipinj/EasyLoggingPP