The compiler is what takes this code, and translates it into the machine code
How can I see the original C code after compilation in bin
so are you asking how to reverse it? you should search up reverse engineering and go from there. you will need to use a decompiler, know a bit of assembly and there is still no guarantee of success, that you will be able to get all the original code. it will also get harder if the program originally had more than one file or some sort of hiding technique to randomize the code (obfuscation). You will need to do alot of work to get even a bare-bones resemblance of the original code. here is the Wikipedia link for the topic: http://en.wikipedia.org/wiki/Reverse_engineering
HOWEVER, IT MAY BE ILLEGAL IN YOUR AREA, Depending on what you do with it, please don't get in trouble!
NOTE: if this post isn't allowed, someone please let me know and i'll take it down immediately.
EDIT: It can also be called decompiling as well i believe.