As of version 0.12.0, Log4cxx requires a minimum C++ version of C++11.

Log4cxx requires the following software to build and/or run correctly:

Dependency Name	Version	Dependency Type	Homepage
Apache Portable Runtime(APR)	>=1.5.4	Compile/Runtime	https://apr.apache.org
APR-Util	>=1.5.4	Compile/Runtime	https://apr.apache.org
gzip	any	Test/Runtime(optional)	https://gzip.org
sed	any	Test	N/A
zip	any	Test/Runtime(optional)	N/A

APR+APR-Util

The Apache Portable Runtime(APR) provides the cross-platform backend for Log4cxx. Both APR and APR-util need to be installed and available on your system.

sed+gzip+zip

These applications are needed to test Log4cxx. gzip and sed are generally installed by default on Linux. zip may not be installed by default; check your distribution's documentation for information on how to install these applications.

For Windows, you will have to install those tools through a system such as MinGW, cygwin, or MSYS2.

gzip and zip only needed during runtime if you are compressing the log files, for example by setting a rollover policy which ends in .gz or .zip.

Using std::format instead of fmt::format

The LOG4CXX_XXXXX_FMT logging macros use the macro LOG4CXX_FORMAT_NS to select the format function version.

Use the CMake option LOG4CXX_FORMAT_NAMESPACE=std to set the default value for LOG4CXX_FORMAT_NS to std. If LOG4CXX_FORMAT_NAMESPACE is not specified when Log4cxx is built, the default value for LOG4CXX_FORMAT_NS is fmt.

Setting LOG4CXX_FORMAT_NAMESPACE=std when building Log4cxx does not prevent an application from using the {fmt} library. An application developer can choose the implementation by adding LOG4CXX_FORMAT_NS=std or LOG4CXX_FORMAT_NS=fmt to the target_compile_definitions command in their CMakeLists.txt. If that preprocessor macro is absent, the LOG4CXX_XXXXX_FMT logging macros will expand to the default value of LOG4CXX_FORMAT_NS defined when Log4cxx was built.

Optional Dependencies

The following table lists CMake options that require additional dependencies.

CMake option	Dependency Name	Version	Dependency Type	Homepage
LOG4CXX_MULTIPROCESS_ROLLING_FILE_APPENDER	Boost	any	Compile/runtime. Not required if your compiler supports C++17	https://boost.org
ENABLE_FMT_ASYNC	{fmt}	9+	Compile/runtime	https://github.com/fmtlib/fmt
ENABLE_FMT_LAYOUT	{fmt}	9+	Compile/runtime	https://github.com/fmtlib/fmt
LOG4CXX_ENABLE_ODBC	unixodbc	any	Compile/runtime (not on Windows)	https://www.unixodbc.org/
LOG4CXX_ENABLE_ESMTP	libesmtp	any	Compile/runtime (not on Windows)	https://github.com/libesmtp/libESMTP
LOG4CXX_QT_SUPPORT	Qt	5	Compile/runtime	https://www.qt.io/download
LOG4CXX_CFSTRING	Mac OS/X Core Foundation	any	Compile/runtime	https://developer.apple.com/documentation/corefoundation

Default CMake option values

All the above CMake options default to OFF except for the {fmt} library options.

If the {fmt} library is found (by find_package(fmt 7.1 QUIET)) when Log4cxx is built, the options ENABLE_FMT_ASYNC and ENABLE_FMT_LAYOUT default to ON.

A note on C++ version and Boost

By default, Log4cxx requests C++20 features. This is to avoid 3rd party dependencies as much as possible. If C++17 is not available, a search for Boost will be taken and those libraries will be used instead. If you would prefer to use Boost, there are two options you have:

1. Pass -DPREFER_BOOST=ON to CMake when compiling. This will ignore the results of the tests that check for the standard version of components that are required. Note that this will switch all components, regardless of the C++ version in effect at compile time.
2. Revert to an earlier standard using -DCMAKE_CXX_STANDARD=11 for example. This will still to check for standard versions of required components, but it will fall back to using Boost for newer components added in C++17.

Licenses(direct dependencies only)

Dependency	License
APR, APR-util	Apache License, Version 2.0
Boost	Boost License, Version 1.0
{fmt}	MIT
unixodbc	LGPL
libesmtp	LGPL
Qt	Refer https://www.qt.io/licensing/
Mac OS/X Core Foundation	APSL 2.0