"Real time" is commonly assumed to mean that you can't use a garbage collected language or need to be extremely careful doing so because random pauses of 100ms

"Real time" is commonly assumed to mean that you can't use a garbage collected language or need to be extremely careful doing so because random pauses of 100ms break your constraints. If you're in a situation where the overhead of a couple of function calls is unacceptable, regexes are totally unacceptable and you need to write custom character manipulation. This situation is really rare and in almost all business cases, using C is inappropriate.