Using #include for variables

Projects Programming
1

I'm doing some stuff with an LCD and have generated a bunch of custom characters using the method in the Arduino LiquidCrystal libraray. So now I have 5 or 6 declarations that look like this (except they're all different obviously):

byte example[8]={
   B11111
   B11111
   B11111
   B11111
};

So my question is, instead of having these definitions in my .ino file, can I use something like:

#include "characters.inc"

Where characters.inc is the definitions saved in a notepad file or whatever.
And then just have the #include statement in my code? This way it's not so cluttered in the main.

2

Yes you can.

I have used this method to some extent. However it may not work under all scenarios in the IDE, that being said, I've had it working in a library.

With a quick test, you have to use .h or .cpp files so the IDE will see it during compilation.

char myArr[] = {
  #include "mydata.h"
};

void setup() {
  Serial.begin( 9600 );
  Serial.print( myArr );
}

void loop() {}

'a',
'b',
'c',
'd',
'e',
'f',
'g',
'h',
0,
3

Awesome. That worked perfectly. The only thing is that at first it didn't recognize byte as a type, so I had to add #include <Arduino.h> to the top of my header file. Also, not sure if this was completely necessary, but I put the .h file in my sketch folder. Anyway, thanks man.

4

byte is defined in Arduino.h

To avoid including the header just for byte, you can use unsigned char instead, as that is what byte really is.

5

Will it use more memory? Or are they both 8 bits?

6

They are exactly the same thing.

byte is defined as:

typedef unsigned char byte;

so its just an alias to an unsigned char, and yes unsigned char is 8-bits wide.
typedef has other implications, however they are equal in this circumstance.

7

Good to know. Thanks.