Why do all the C files written by my lecturer start with a #?

Question

Why do all the C files written by my lecturer start with a #?I'm going through some C course notes, and *every* C program source file begins with a single `#` on the first line of the program.Then there are blank spaces, and following that other stuff followed by the `main` function.What is the reason for the `#`?(It's out of term now and I can't really ask the chap.)Here's an example (there is an extra line at the end of the closing `}`) # #include <stdio.h> int main() { printf("Hello, World!"); return 0; }

Answer 1

It is part of the syntax, for sending commands to the compiler....

#include : inserts the contents of the header file

#define : declares a macro

#ifdef : used to conditional compilation