How to read the gpt partition table

To read the MBR partition table we use an offset of 0x1be , similarly what is the offset for reading the GPT partition table entries (ie, number of partitions and their sizes).

Iam writing a C program using "gdisk" to create the partitions,I need to write the filesystems onto these partitions. So for this i need to read the gpt header to get the number of partitions and their allocated sizes.