Number 1 and letter l

Dear devs,
I have tried looking for people with a similar problem, but no luck there.
I know this is a detail, but there is where the devil lies sometimes.

Inside the Arduino IDE the letter O and number 0 are slightly different in shape and therefore perfectly distinguishable.
The small letter l and the number 1 are exactly the same.
It has caused me some issues in the past, so I hope there is a workaround, or a future change to this design, similar the symbols for 0 and O.

Thanks for the otherwise beautiful Software
cheers Dave

DavidWimmer: I have tried looking for people with a similar problem, but no luck there.

Even though your search apparently missed the people who discussed this previously on the forum, you've found one now in me.

DavidWimmer: Inside the Arduino IDE the letter O and number 0 are slightly different in shape and therefore perfectly distinguishable.

You're more easy going than I. I don't even like how similar those two are in the screenshot you shared.

DavidWimmer: I hope there is a workaround

Sure. Do this:

(In the Arduino IDE) File > Preferences

Click the link at the line following "More preferences can be edited directly in the file". - This will open a folder named something like "Arduino15" (depending on which operating system you're using).

Close all Arduino IDE windows.

In the "Arduino15" folder, open the file named "preferences.txt" in a text editor.

Search for the line in the file that looks something like this:

editor.font=Monospaced,plain,12

Change the "Monospaced" to the name of your preferred font. If you're using Windows, I recommend using "consolas":

editor.font=consolas,plain,12

Don't bother messing with the "plain" or "12" parts. The IDE ignores the font style setting and you can change the font size more conveniently via the Arduino IDE's File > Preferences GUI.

Save the "preferences.txt" file.

Start the Arduino IDE.


I'm happy to inform you that the default font in Arduino IDE 2.x is more usable. For example, it uses Consolas by default on Windows: https://github.com/microsoft/vscode/blob/c6d6bda7197d0546d21465dc7f6fa849a146504f/src/vs/editor/common/config/editorOptions.ts#L3680-L3682