C/C++ Source and Header Files

Key Word(s): C++, source files, header files

Key: :large_orange_diamond: - Code Example :large_blue_diamond: - Code Exercise :red_circle: - Code Warning
Previous: Compilation Basics
Next: C Preprocessor

Source Files

The majority of our code will be written in source files.

Header Files

Header files usually contain function declarations but can sometimes also contain functions implementations, e.g. inlined functions.
Header files can be used used to share these declarations and macro expansions across multiple files.

C++ header file extensions:

• .h
• .hpp

C header file extensions:

• .h

Example: print_hello_world()

void print_hello_world(void);

#include <stdio.h>
#include "hello_1.h"

int main(void){
  print_hello_world();
  return 0;
}

void print_hello_world(void){
  printf("Hello, World!\n");
}

• If hello_1.h is not included in hello_1.c, print_hello_world() would not be known by the main function
• Programs compiled with gcc are parsed top-down

Luckily for us, the C Preprocessor replaces the #include "hello_1.h" line with all of the code found in hello_1.h.

:large_orange_diamond: Hello World Header Files!
This example also introduces name mangling which we will learn more later in the semester.

Next: C Preprocessor