Struct to web style string
Yeah, without snprintf and sprintf it gets a bit tedious, but I think this code is actually quite clear. You use your horizontal and vertical whitespace very well, and it's clear what you're doing with each block of code. You have also controlled for any possible issues that might come up (null pointer, insufficient buffer length, etc). Maybe there's a more concise way to do it, but in terms of clarity and maintainability I think this code will suffice.