How do you determine the size of a file in C?

Question

How can I figure out the size of a file, in bytes?

#include 

unsigned int fsize(char* file){
  //what goes here?
}

Answer 1

And if you're building a Windows app, use the GetFileSizeEx API as CRT file I/O is messy, especially for determining file length, due to peculiarities in file representations on different systems ;)