Log for C++ Project

 | Log for C++ Project Page on Sourceforge  | Last Published: 2012-11-29  |

What is log4cpp?

Log4cpp is library of C++ classes for flexible logging to files, syslog, IDSA and other destinations. It is modeled after the Log4j Java library, staying as close to their API as is reasonable.


Sources are available from SourceForges download page.
We do not supply binaries yet, because of the numerous incompatible ABIs (e.g. g++ 2.95 vs 2.96 vs 3.0 vs 3.2) and different package formats.
An older version of log4cpp (0.2.5) is available in Debian stable, see http://packages.debian.org/stable/libs/liblog4cpp0.html.
FreeBSD users can find log4cpp (0.2.7) in the ports collection, see http://www.freebsd.org/ports/devel.html
The people of the Datagrid Project Central Repository have published the source and binary RPMs they use theirselves. These are for RedHat Linux 6.2.
Log4cpp includes support for building RPMs, so building your own from the source tar-ball is as simple as

rpm -ta log4cpp-x.y.z.tar.gz


Building Log4cpp


As of version 0.2.0 log4cpp can be build using autoconf on platforms that support it. Simply do:

make check
make install

This will install log4cpp under /usr/local. To install in another localation specify --prefix=<location> when running configure.

Options for ./configure

Besides the usual ./configure options like --prefix a few others are available:
Include support for logging to IDSA (http://jade.cs.uct.ac.za/idsa/index.html). This will give you an IdsaAppender Appender class.
Enable multi-threading support using omniORB4's omniThreads MT abstraction library (http://www.omniorb.org). configure expects the omnithread header files to reside in <path-to-omniORB>/include and the library in <path-to-omniORB</lib, i.e. not in a platform specific subdirectory. Create symlinks where necessary.
NB. omniORB4 is required: omniORB3 will not suffice as it lacks sufficient support for thread specific data. At the moment (August 2002) omniORB4 is in beta, however most parts and specifically the threading library appear to be quite stable.
Enable multi-threading support using the 'pthread' POSIX threads library. This option is mutually exclusive with --with-omnithreads.
Enables generation of API documentation by Dimitri van Heeschs Doxygen tool (http://www.doxygen.org/). Defaults to yes if doxygen can be found in the search path.
If doxygen is enabled, have it generate HTML formatted documentation.
If doxygen is enabled, have it generate LaTeX formatted documentation.
Let Doxygen use the 'dot' tool of GraphViz (http://www.graphviz.org) todraw its graphs.

Build notes for specific platforms

*nix - g++ compiler
Log4cpp should build whitout modification on any decent *nix system with g++ and GNU make. The primary development platform is RedHat Linux 7.3, which has g++ 2.96-rh, but the aim is to be compatible with from g++ 2.95 and up. When g++ 3.x has been widely adopted we may drop support for older g++ versions.
Solaris - Sun CC compiler
Compilation with Suns CC compiler requires setting some enviroment variables. Also static libraries appear not to work. In short do:
CC=CC CXX=CC LD="CC -KPIC" ./configure --disable-static
Win32 - VS2010
Use the workspace and project files in subdirectory msvc10. (You may need to adjust include/log4cpp/config-win32.h and the project files to your particular needs)
Win32 - MSVC++ 6
Use the workspace and project files in subdirectory msvc6. You may need to adjust include/log4cpp/config-win32.h and the project files to your particular needs.
Win32 - MSVC++ 5
Building log4cpp with MSVC++ 5 is not supported and will not be, unless someone can find a way to do so without mutilating the source code.
Win32 - Borland C++ Builder 5
Use the project and make files in subdirectory bcb5.
Win32 - Cygwin
Use './configure; make; make install'.
Be warned that there have been very few success or failure reports for this platform, so either it works very smoothly or noone actively uses log4cpp with Cygwin :-)
Edit include/log4cpp/config-openvms.h if you need different settings.
This has been tested on OpenVMS Alpha v7.3 and Compaq C++ V6.3-020 only.
1) Copy the src and include directory (including all its contents and subdirectories) onto your OpenVMS system.
2) Compile each source file (*.CPP and *.C in the src directory) one by one by the following command,
cxx /include=("/a1\$dkb0/user/tony/project/log4cpp/include") /define=(__USE_STD_IOSTREAM,__OPENVMS__) /repository=a1$dkb0:[user.tony.project.log4cpp.repository] APPENDER.CPP
cxx /include=("/a1\$dkb0/user/tony/project/log4cpp/include") /define=(__USE_STD_IOSTREAM,__OPENVMS__) /repository=a1$dkb0:[user.tony.project.log4cpp.repository] APPENDERSKELETON.CPP
Please substitute a correct path for your include directory. A unix-style directory name is requied in the /include parameter. In this example, the pathis A1$DKBO:[USER.TONY.PROJECT.LOG4CPP.INCLUDE]
A repository directory is also specified here as A1$DKB0:[USER.TONY.PROJECT.LOG4CPP.REPOSITORY].
3) Create a static library, LOG4CPP.OLB
lib/create log4cpp
4) Put all compiled OBJ files into the LOG4CPP.OLB
lib/insert log4cpp appender
lib/insert log4cpp appenderskeleton
5) Link a program with log4cpp.olb. e.g:
cxx /include=("/a1\$dkb0/user/tony/project/log4cpp/include") /define=(__USE_STD_IOSTREAM,__OPENVMS__) testlog4cpp.cxx
cxxlink /repository=a1$dkb0:[user.tony.project.log4cpp.repository] testlog4cpp,log4cpp/library


As of version 0.2.1 this library is licensed under the Lesser General Public License instead of the General Public License. No further license changes are planned :-).

Log for C++ (short name: log4cpp), a C++ library for flexible logging.
Copyright (C) 2000-2002 LifeLine Networks bv
Copyright (C) 2000-2002 Bastiaan Bakker
Portions Copyright others, see file THANKS and source code.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

API Documentation

API Documentation generated by Doxygen can be found here.
The Solaris Developer Connection features an article by Mo Budlon on using log4cpp 0.2.x, called 'Logging and Tracing in C++ Simplified'. Recommended reading if you trying to figure out how to use log4cpp!




1.1. What is Log for C++?

Log for C++ is a library of C++ classes for flexible logging to files, syslog and other destinations. It is modeled after the Log for Java library (http://jakarta.apache.org/log4j/), staying as close to their API as is reasonable.

1.2. How is Log for C++ related to Log4j? Is it a straight port?

Log for C++ strives to supply a similar interface for logging in C++ as Log4j provides in Java. However the implementation is not a translation of the Java code. So in that sense it is not a 'port' of Log4j. Of course Log for C++ does owe many of its concepts to log4j.

1.3. What is the name of this project, 'Log for C++' or 'log4cpp'?

The 'official' long name of the project is 'Log for C++', but in practice, the short name, 'log4cpp' has proven more convinient.

1.4. Under which license is Log for C++ available?

As of version 0.2.1 Log for C++ is released under the GNU Lesser General Public License (LGPL). Versions before that have been released under the GPL. See the license discussion on the forum at SourceForge for the motivations behind switching from GPL to LGPL.

1.5. Our legal department doesn't like the LGPL, can you release Log for C++ under license XYZ?

Long answer: Technically it may be possible if every contributor agrees, which due to their growing number has become increasingly difficult. But even if that could be overcome it will not happen.
Of course the LGPL does grant you the opportunity to choose the GPL instead of the LGPL, but I bet XYZ != GPL.


See building


3.1. I've succesfully compiled log4cpp, now how do I use this stuff?

Have a glance at Simple example and Properties file example. For some small examples using log4cpp, see the 'tests' subdirectory. Also see the documentation section for a pointer for API documentation and more usage information.

3.2. Is log4cpp thread-safe?

The same instance of the log4cpp::Category object (a logger) can be used from different threads simultaneously without explicit synchronization. Concurrent access to the appenders will be prevented by the logger object itself. It will lock internal mutex each time when it comes to writing into appenders. So, it is safe, for example, to write from the multiple threads to the same logger which appends to the same file. Although, log4cpp is configured in such a way that two different loggers append to the same appender (it may be a file), then there will be no way for the logging framework to arrange proper addition and things can get mixed up. So this way of configuration is not recommended.

3.3. What are possible format characters for the custom log message?

PatternLayout supports following set of format characters:
  • %% - a single percent sign
  • %c - the category
  • %d - the date\n Date format: The date format character may be followed by a date format specifier enclosed between braces. For example, %d{%H:%M:%S,%l} or %d{%d %m %Y %H:%M:%S,%l}. If no date format specifier is given then the following format is used: "Wed Jan 02 02:03:55 1980". The date format specifier admits the same syntax as the ANSI C function strftime, with 1 addition. The addition is the specifier %l for milliseconds, padded with zeros to make 3 digits.
  • %m - the message
  • %n - the platform specific line separator
  • %p - the priority
  • %r - milliseconds since this layout was created.
  • %R - seconds since Jan 1, 1970
  • %u - clock ticks since process start
  • %x - the NDC
  • %t - thread name
  • By default, ConversionPattern for PatternLayout is set to "%m%n".


    4.1. I get 'Naming collision for 'ERROR' detected. Please read the FAQ for a workaround.'

    This is caused by the rudeness of some platforms, which mutilate the namespace with some blunt #defines. To be more precise, the Win32 API includes #defines of 'ERROR' and 'DEBUG'. Since the preprocessor is unaware of C++ naming scopes this results in reserving the words ERROR and DEBUG litterally everywhere. In particular this conflicts with log4cpp::Prioritiy::ERROR and log4cpp::Priority::DEBUG. These latter two names come from log4j, so they are not something we made up ourselves.
    They Win32 authors should not have rudelessly claimed these generic names through the preprocessor. There are much better alternatives:
    1. If they use it as an integer constant, declare it using a language construct. Either 'enum {ERROR=1};' or 'static const int ERROR=1;' would do fine.
    2. Use a less generic name like WIN32API_ERROR to make naming conflicts less likely
    3. In case they use it as a flag for conditional compilation, use '#define DEBUG DEBUG' and '#if defined(DEBUG)'. In that case the preprocessor would simply replace all occurrences of 'DEBUG' in the source code with 'DEBUG', in effect leaving everything intact.

    Of course the proper solution would be if the offending party would use one of the above methods, but we could have to wait some time for this to actually happen. As an alternative log4cpp can workaround these #defines. The workaround code is enabled by doing #define LOG4CPP_FIX_ERROR_COLLISION 1 before #including any log4cpp header files and after #including all platform headers. For Win32 platforms this #define has already been included in log4cpp/config-win32.h.

    Once log4cpp has been updated to the log4j 1.2 API we can get rid of this problem by adopting the new names for log levels.

    4.2. I am trying to compile/link the log4cpp package using the SunWorkshop compiler (CC) on a Solaris 7 machine. The library builds, but the testmain code fails to link properly.

    A proper solution for this problem has not been found yet (suggestions are welcome), but James Emery reported success with the following workaround:
    • Disable building of the static library
    • Change the linker from /usr/ucb/ld to CC and enable 'place independent code' (pic).
    In short, configure with:
    export LD="CC -Kpic" && ./configure --disable-static

    4.3. ./configure fails to detect 'snprintf()' on platform XYZ.

    ./configure does not just check for the presence of a snprintf() function but for C99 compliancy as well. In particular, snprintf() should strictly honour the 'string size' parameter to avoid potential buffer overflow problems. log4cpp falls back to an alternative snprintf() implementation if the OS does not provide a correct one.


    Simple example

    Sample main.cpp file that logs onto console and into file program.log. Loggers and appenders are created and configured manually. Example makes use of both function-style logging and stream-style logging.

    // main.cpp
    #include "log4cpp/Category.hh"
    #include "log4cpp/Appender.hh"
    #include "log4cpp/FileAppender.hh"
    #include "log4cpp/OstreamAppender.hh"
    #include "log4cpp/Layout.hh"
    #include "log4cpp/BasicLayout.hh"
    #include "log4cpp/Priority.hh"
    int main(int argc, char** argv) {
    	log4cpp::Appender *appender1 = new log4cpp::OstreamAppender("console", &std::cout);
    	appender1->setLayout(new log4cpp::BasicLayout());
    	log4cpp::Appender *appender2 = new log4cpp::FileAppender("default", "program.log");
    	appender2->setLayout(new log4cpp::BasicLayout());
    	log4cpp::Category& root = log4cpp::Category::getRoot();
    	log4cpp::Category& sub1 = log4cpp::Category::getInstance(std::string("sub1"));
    	// use of functions for logging messages
    	root.error("root error");
    	root.info("root info");
    	sub1.error("sub1 error");
    	sub1.warn("sub1 warn");
    	// printf-style for logging variables
    	root.warn("%d + %d == %s ?", 1, 1, "two");
    	// use of streams for logging messages
    	root << log4cpp::Priority::ERROR << "Streamed root error";
    	root << log4cpp::Priority::INFO << "Streamed root info";
    	sub1 << log4cpp::Priority::ERROR << "Streamed sub1 error";
    	sub1 << log4cpp::Priority::WARN << "Streamed sub1 warn";
    	// or this way:
    	root.errorStream() << "Another streamed error";
    	return 0;
    Console output for that example
    1352973121 ERROR  : root error
    1352973121 ERROR sub1 : sub1 error
    1352973121 WARN sub1 : sub1 warn
    1352973121 WARN  : 1 + 1 == two ?
    1352973121 ERROR  : Streamed root error
    1352973121 ERROR sub1 : Streamed sub1 error
    1352973121 WARN sub1 : Streamed sub1 warn
    1352973121 ERROR  : Another streamed error

    Properties file example

    Sample main.cpp file that makes use of logging configuration file log4cpp.properties

    // main.cpp
    #include <log4cpp/Category.hh>
    #include <log4cpp/PropertyConfigurator.hh>
    int main(int argc, char* argv[])
    	std::string initFileName = "log4cpp.properties";
    	log4cpp::Category& root = log4cpp::Category::getRoot();
    	log4cpp::Category& sub1 = 
    	log4cpp::Category& sub2 = 
    	root.warn("Storm is coming");
    	sub1.debug("Received storm warning");
    	sub1.info("Closing all hatches");
    	sub2.debug("Hiding solar panels");
    	sub2.error("Solar panels are blocked");
    	sub2.debug("Applying protective shield");
    	sub2.warn("Unfolding protective shield");
    	sub2.info("Solar panels are shielded");
    	sub1.info("All hatches closed");
    	root.info("Ready for storm.");
    	return 0;

    Configuration file for use with that code

    # log4cpp.properties
    log4cpp.rootCategory=DEBUG, rootAppender
    log4cpp.category.sub1=DEBUG, A1, A2
    log4cpp.category.sub1.sub2=DEBUG, A3
    log4cpp.appender.rootAppender.layout.ConversionPattern=%d [%p] %m%n 
    log4cpp.appender.A2.layout.ConversionPattern=%d [%p] %m%n 
    log4cpp.appender.A3.layout.ConversionPattern=%d [%p] %m%n 
    Console output for that example
    2012-11-14 18:44:58,163 [WARN] Storm is coming
    2012-11-14 18:44:58,166 [DEBUG] Received storm warning
    2012-11-14 18:44:58,170 [INFO] Closing all hatches
    2012-11-14 18:44:58,172 [DEBUG] Hiding solar panels
    2012-11-14 18:44:58,175 [ERROR] Solar panels are blocked
    2012-11-14 18:44:58,179 [DEBUG] Applying protective shield
    2012-11-14 18:44:58,183 [WARN] Unfolding protective shield
    2012-11-14 18:44:58,186 [INFO] Solar panels are shielded
    2012-11-14 18:44:58,190 [INFO] All hatches closed
    2012-11-14 18:44:58,192 [INFO] Ready for storm.

    There are three loggers (including root) and three appenders. Root logger redirects all its own input and input of its descendant onto console. Descendant sub1 writes into two files, filtering output by message priority for second of them. Descendant sub1.sub2 writes also into rolling file. Log file A3.log is rolled over as soon as it reaches limit of 200 bytes, 1 backup log file is kept.


    CVS Repository

    Log4cpp is also available directly through CVS, see the SourceForge CVS page for instructions. CVS currently has two branches:

    MAINfor log4cpp development
    BRANCH_MAINT_0_2for maintainance of log4cpp-stable (0.2.x)

    Each release will receive a tag named REL_x_y_z.

    To start working with a freshly checked out log4cpp revision, run ./autogen.sh first. This will create ./configure and the necessary Makefile.in's. You'll need at least autoconf 2.50, automake 1.6.0 and libtool 1.4.



    WARNING: releases from the development branch are a 'work in progress' and may fail to build, crash or redecorate your desktop.

    1.1.1 - stable branch (26 November 2013)
    Small code and project file fixes.
    1.1rc3 - development branch (18 October 2012)
    Created build projects for MSVC10 (VS2010).
    Small code fixes.
    0.3.4 - development branch (28 October 2002)
    Fixed builds for MSVC6 and MSVC7.
    Removed Log4cppCleanup.
    0.3.3 - development branch (26 October 2002)
    Fixed #628211: build failure on MSVC 6.0.
    Fixed #625811: log facility in RemoteSyslogAppender.
    Possibly fixed #415160: crashes with dynamic library on Solaris 2.6.
    Replaced PatternLayout with a new, faster and more complete implementation.
    0.3.2 - development branch (5 October 2002)
    Fixed #614903: compilation problem on Sun CC 5.3.
    Added missing MSVC6 .dsp files.
    Fixed log facility in RemoteSyslogAppender.
    Fixed relocatability of log4cpp-devel RPM.
    0.3.2rc5 - development branch (5 October 2002)
    Merged #604991: support for setting additivy in PropertyConfig.
    Merged #605143: support for compilation in QNX Neutrino.
    0.3.2rc4 - development branch (16 August 2002)
    Fixed last minute goof ups which prevented compilation on both *nix and Win32 platforms.
    0.3.2rc2 - development branch (12 August 2002)
    Added support for POSIX threads.
    Added PropertyConfigurator.
    Rearranged documentation.
    Fixed various bugs.
    0.3.2rc1 - development branch (19 June 2002)
    Support for Win32 threads added.
    Added NTEventLogAppender.
    Added Win32DebugAppender.
    Fixed NDC context problem if depth > 2.
    Added aclocal support.
    0.3.1 - development branch (4 April 2002)
    Added RollingFileAppender class.
    Fixed bug #572467: invalidated iterator usage.
    Fixed bug #527475: format string bug.
    Fixed bug #530332: missing 'std::' specifiers.
    Handled feature requests #536668, #527760, #527381.
    0.3.0 - development branch (18 Februari 2002)
    Added experimental support for multi threaded applications. This implementation uses omniORB4s threading library. Other threading libraries, such as Boosts, may be used as well, but this has not been implemented yet.
    0.2.7 - stable branch (27 Januari 2002)
    Support for multiple Appenders per Category added (feature request #501360).
    Fixed variable scope bug in SyslogAppender (bug #499315)
    Fixed memory leak in SyslogAppender and RemoteSyslogAppender (bug #499524)
    Fixed compile problem in Filter (bug #)
    Fixed config file parse problem in SimpleConfigurator (bug #500766)
    Added methods for logging at FATAL level (bug #504314)
    Fixed Win32 compile problem (bug #506907)
    0.2.6 (11 December 2001)
    Preliminary support for OpenVMS added.
    PatternLayout, SimpleConfigurator and RemoteSyslogAppender added.
    0.2.5 (11 June 2001)
    Inclusion of support for Borland C++ Builder.
    Library version 1.0.0: this release is not binary compatible with previous ones. (Version update should have been done in 0.2.4).
    0.2.2 (04 March 2001)
    Inclusion of Win32 platform (MSVC++ 6.0)
    0.2.1 (15 Februari 2001)
    license change to LGPL.
    0.2.0 (10 December 2000)
    log4cpp now uses autoconf and automake.



    The latest stable release is 1.1

    As of version 0.3.0 log4cpp has a separate 'stable' and 'development' branches. Releases x.y.z where y is even are considered stable and those where y is odd are experimental (which means that some or all features may be broken).

    Releases of 0.2.x are for bug fixes only, new features will go into 0.3.x and eventually 0.4.x.



    Coding on Log4cpp was initiated by me (Bastiaan Bakker) late 2000. Since then other people have joined the project or contributed code:

    Cedric Le Goater <cedric(at)legoater.com>autoconf setup, various improvements
    Marc Welz <marc(at)jade.cs.uct.ac.za>IdsaAppender
    Lynn Owen <opl(at)agoby.com>MSVC++ support
    Steve Ostlind <s.ostlind(at)pentasafe.com>MSVC++ support, various fixes
    Marcel Harkema <marcel(at)debian.org>Debian packaging
    Uwe J├Ąger <jaeger(at)varial.de>Borland C++ Builder support
    Walter Stroebel <walter.stroebel(at)lifeline.nl>RemoteSyslogAppender
    Glen Scott <glen_s(at)yahoo.com>PatternLayout, SimpleConfigurator
    Tony Cheung <dragonman(at)asiayeah.com>OpenVMS support
    Alex Tapaccos <ATapaccos(at)redfig.com>DailyRollingFileAppender
    Brendan B. Boerner <bboerner(at)texas.net>Multiple Appender support for Categories
    Paulo Pizarro <paulo.pizarro(at)digitro.com.br>RollingFileAppender
    David Resnick <dresnick(at)mobilespear.com>NTEventAppender, integration work
    Aaron Ingram <ai8(at)yahoo.com>MSThreads support
    Alan Anderson <alan(at)rushmore.com>Win32DebugAppender, PropertyConfigurator
    Emiliano Martin <emilianomc(at)terra.es>PThreads support
    Alexander Perepelkin <sanchouss_(at)users.sf.net>Project maintenance, improvements, fixes


    Other projects

    Log4cpp is one of many ports/implementations of the Log4j API. Here's an incomplete list:

    log4cAn implementation in C by Cedric Legoater
    log4cplusAn indepent C++ implementation by Tad Smith. Worth checking out if you don't like Log4cpp for some reason.