I’m trying to save an array of phone numbers (let’s say 10 or 20) in the (retained) Backup-RAM of the Particle Electron. To save memory I’d scrap the leading “+” and only store numbers beginning with the country code (eg 49 for germany).
I’m using retained as the content should be available after sleep and the numbers should be changed over the air.
Using the String data type would be the worst (if even possible) solution, as it always consumes a bunch of bytes in memory.
Using retained char phone would be possible, but this also consumes 16 bytes for a number that could saved in a 8-byte unsigned integer. In Addition, I’ve no Idea how to create a multi-dimensional array of chars (like phones)
Can give me a hint how to solve this issue?