networking - buffer sizes

[stav]

^
why is it that people make their buffers 256. 512. 1024 bytes long when sending and receiving messages?

why not something like 649 or 34 bytes?

[NoXzema]

It's generally because they're allocating a buffer for the maximum size of the message which is usually in increments of 2^x. Sometimes there are alignment issues and it can affect performance ( https://en.wikipedia.org/wiki/Data_structure_alignment ). In most cases, however, it doesn't and there's nothing wrong with allocating a buffer of size 649, assuming you know that's the size of the message you're receiving.