It is similar but different from ansi c.
Firstly, compiling and linking are two different steps not handled by the same program.
On sans you can use them by running
9 9c hi.c 9 9l hi.o -o hi
This will compile the source file hi.c, creating hi.o
Then, 9l, the linker, will create the executable hi from hi.o
The prefixing 9 isn't standard to plan9, but is used on sans to avoid collisions in binary naming provided by plan9port.