Introduction: Arduino Auto Formatting Listings

The default way that the Arduino programming environment handles braces (curly brackets) has annoyed me for years (see the first image).

I much prefer the braces to be separated out onto their own lines (see the second image). I find this much easier to de-bug. I gather it is called 'Allman' style.

When editing your sketches, pressing CTRL+T will re-format the whole program code beautifully, but (by default) to the style which I don't like.

It is easy to adjust the auto formatter's default actions (not only for the braces, but for a vast range of options).

The process is to find the file called 'formatter.conf', copy it to your local preferences file and make a one-line addition.

Step 1: Making the Change

Find the 'formatter.conf' in the main Arduino installation folder.

Mine was in the folder called C:/Program Files (x86)/Arduino/lib/

Copy the file (CTRL+C) and paste it into your own local preferences folder.

To find this folder, double-click one of your sketches and then go to File>Preferences and you will see a window similar to that shown here.

Paste the 'formatter.conf' file into your own preferences folder (CTRL+V). (It will be alongside your own 'preferences.txt' file).

Step 2: Make the Change to the Preferneces

You may have to close your Arduino environment before making the following change to this file?

If you double-click on your newly copied 'formatter.conf' file, you may have to tell your computer to open it in Notepad or similar.

Finally add the line


into the 'formatter.conf' file. I don't think the position really matters??

I added a comment above it.

(Moving the 'formatter.conf' file into your own preferences folder, means that the change will 'stick' even if you update your Arduino installation).

Step 3: Making Other Changes

I believe that a huge range of default options can be changed by adding similar lines.

The guidelines are here: