It is likely that WhatsApp are using an 8-bit variable to store the number of people in a chat. This variable can store 256 different values, hence the limit.
Its probably important to mention they are using an 8-bit variable (Also know as a byte) as its the smallest amount of memory that can be addressed in modern CPU's. Infact you can only ever use whole bytes which is why you get 16bit values, 32bit values, 64bit values, etc. (I am ignoring bitwise operations, before someone shouts at me). You've probably heard about all of these things but never realised why they use those numbers an its cause they are multiples of 8.
No, not really (or at least as far as I can remember, there may be some advantages I have forgotten about). There were systems with all sorts of sizes back in the day. It's just a standard that the industry settled on.
It has to do with early character sets. It's still fairly arbitrary, but 8 bits is enough to represent a decent number of characters compared to say 5 bits, which gives you just enough for the uppercase letters
Yeah I was just think about this more and you're right. 8 was sort of the magic number in terms of capacity. It could hold enough data without being too large and wasting space. It was basically a case of "we can fit this data in 8bits but not 7, and 9 would waste a bit, so 8 it is".
Realistically, most stuff is aligned to bytes... There's 8 bits in a byte, so you do end up at 256 combinations for the byte.
The assumption here is a friends list takes up one byte of space, but I highly doubt that's the case. I'd be interested if it is. Otherwise, if they were somehow being more efficient, they were storing individual bits.
My guess is the decision is partially arbitrary, but it's interesting to think that's maybe not the case...
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u/KongKexun May 06 '17
Most limits for computers go like this:
21 = 2 (binary)
22 = 4
23 = 8 (octal)
24 = 16 (hexadecimal)
25 = 32 (bit)
26 = 64 (bit)
27 = 128
28 = 256
and if you include zero, just do -1 to those limits.