i need to store a opengl built solid in a file . i am using c coding.
What do you mean? You have the data, and you want to dump it into a file? If so, you can pick the format you want. If you want it in a certain format, then you need the docs to see how the file is written in that format.
A simple ASCII dump will be easy to do, and will allow you to import/export from your program.