# How to import the toolkits¶

To include OpenEye libraries in a C++ program the appropriate header files must be included at compile time. All OpenEye libraries require that the openeye.h header file is included first. Then additional OpenEye libraries can be included, for example, the OEChem TK library:

include <openeye.h>
include <oechem.h>


Every OpenEye library resides in its own C++ namespace. It is often useful to use the following idiom to produce shorter, more readable code:

using namespace OEChem;


Since OEChem TK‘s objects and functions have unique names, there is little chance to have a name clash with this particular idiom.