C programming problem, help!

I am trying to use provided by Redhat linux in /usr/include/, but I don't know how to initialize the real and image part of the complex number. any one knows how to use complex.h, please kindly provide a code segment.


BTW, if I want to handle file bigger than 2G, it seems I need to declare file offset as off64_t, but my complier said this off64_t no declared. What's the problem

Thanks