what is far pointer in C
It's a historical anachronism from segmented architectures such as the 8086.
Back in the days of yore there was the 8080, this was an 8 bit processor with 16 bit address bus, hence 16 bit pointers.
Along came the 8086, in order to support some level of backward compatiblity it adopted a segmented architecture which let use use either 16 bit, 20 bit or 32 bit pointers depending on the day of the week. Where a pointer was a combination of 16 bit segment register and 16 bit near offset. This lead to the rise of tiny, small, medium, large and huge memory models with near, far and huge pointers.
Other architectures such as 68000 did not adopt this scheme and had what is called a flat memory model.
With the 80386 and true 32 bit mode, all pointers are 32 bit, but ironically are now really near pointers but 32 bit wide, the operating system hides the segments from you.