[Gmsh] Extrude command through Gmsh

[rahulsn at iitk.ac.in]

Dear Takuya OSHIMA,

      I have a question regarding the making of a geometry file through
c++ code using Gmsh API. I have successfully created some basic
geometries using your C++ code. I want to develop a 3-D geometry for
which i will need to use the extrude command. I tried a lot to
implement the extrude command using my code but i am still not able
to execute the extrude command. If you know anything about this,
please tell me how to do this. This will help me to move forward
with my project.

Thanks,
Rahul