eolas/zk/Create_C_header_file.md

tags
C

In order to create a file that you can import into other C files you need to create a header file.

Remember that this isn't really a module since .h files and #includes are just text substition

In fact you create a .h header file which links to a .c file which actually contains the code you want to import.

Let's say we want to create a "module" that handles connecting to WiFi:

// wifi.h

#ifndef WIFI_H
#define WIFI_H

void wifi_connect(void);

#endif

In the .h file we just define the function signature and put checks (so it doesn't get redefined).

Then the implementation file:

// main/wifi.c

// Add any header files or auxiliary functions that the main (wifi_connect)
// function will require here

void wifi_connect(void) {}

Then in your main entrypoint:

// main/main.c
#include "wifi.h"
wifi_connect()