libdxfrw 
libdxfrw is a free C++ library to read and write DXF files in both formats, ascii and binary form. It is licensed under the terms of the GNU General Public License version 2 (or at you option any later version).
A fork of http://sourceforge.net/projects/libdxfrw
This project is an attempt to refactor out QGIS specific code paths from libdxfrw, so that fixes from the QGIS internal copy can be upstreamed to https://github.com/LibreCAD/libdxfrw (or alternative)
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Building and installing the library
mkdir build
cd build
cmake ..
make
sudo make install
For non-debug version:
mkdir release
cd release
cmake -DCMAKE_BUILD_TYPE=Release ..
make
sudo make install
== UBUNTU/Mint Folks ==
mkdir release
cd release
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX:PATH=/usr .. && make all
make
sudo make install
== Example usage of the library ==
See how we use it in LibreCAD V3 : https://github.com/LibreCAD/LibreCAD_3/tree/master/persistence/libdxfrw