Using functions in header files [closed]

Question

I want to include a function in my sketch I moved to a .h file.

I did it as follows:

My code:

#include "header.h"

void setup() {
  fct();
}

void loop() {

}

My header:

#include "Arduino.h"
#ifndef MYHELPERS_H
#define MYHELPERS_H

void fct() {
// stuff
}

#endif

The same process seems to work for variables but the IDE says this function in not declared in this scope...

I don't understand what I'm doing wrong...

Thanks guys!

for me it compiles. do you have the header file as tab in IDE? — Juraj, Mar 20, 2021 at 5:23
Where exactly does your header file lie? In the same folder as the main sketch? Or in the libraries folder? — chrisl, Mar 20, 2021 at 11:43
This is not the way you separate your project in modules. In a header file you declare what your module offers publically. The implementation goes into another C++ file and this will be compiled separately. -- Please get a good book on basic C++ and/or Arduino programming and read it. This issue is far too broad to be answered in a SE/Arduino question. — the busybee, Mar 20, 2021 at 14:22
This header file was created with the new file button in the Arduino editor and it resides in the same folder as the main sketch. — Spyro 999, Mar 21, 2021 at 14:37

Spyro 999 · Accepted Answer · 2021-03-21 14:39:51Z

0

I found a solution somewhere else on internet...

This portion:

#ifndef MYHELPERS_H
#define MYHELPERS_H

Was not written correctly... "MYHELPERS_H" should've been replaced by the name of my file. Now it works just fine.

answered Mar 21, 2021 at 14:39

Spyro 999

193 bronze badges

2

there is no relation between the include guard macro name and the name of the file. this answer is wrong.
– Juraj ♦
Mar 21, 2021 at 14:52
It's weird but it fixed my problem
– Spyro 999
Mar 22, 2021 at 15:58
Maybe the guard macro name has to be the name using in the #include of the main sketch but it works now I have done this
– Spyro 999
Mar 22, 2021 at 16:00
no. #include takes a file name. and it doesn't care about the content of the file
– Juraj ♦
Mar 22, 2021 at 16:06
1

I'm on a work trip right now and my pc is home
– Spyro 999
Mar 24, 2021 at 18:29

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