I would say, unless there's a performance reason not to, always use asprintf for every string operation.

For string heavy workload, C is ideal, provided that you don't use C string functions.

You can always allocate a very large buffer and do your string operations there, using memncpy and the assorted functions which can be inlined in many architectures and be really fast.

Then you can dispose of the buffer really quickly with one call or reuse it for later operations by simply setting a few pointers to initial status...

If you have large data sets and need maximum performance I agree, but a lot of day to day string processing works on small data sets and isn't very performance-sensitive.

As a newcomer to C, why is it that the C standard library doesn't get updated? Newer languages seem to place a lot of emphasis on getting their standard libraries as useful as possible. It's odd to be told not to use the standard library functions but to write my own instead. I'm really doubting I can just sit down and hammer out string functions superior to string.h.

Just my guess: C doesn't depend as much on its standard library as other languages (which has its good and bad sides), and this also means that fixing the standard library isn't very high on the priority list of the C committee, because everybody knows that for any serious work the stdlib isn't suitable anyway.

The C stdlib is basically the lowest common denominator which enables writing very simple UNIX-style mostly-cross-platform command line tools, but not much else. For anything serious you either call OS API functions directly, or resort to specialized third-party libs.

Attempting to 'fix' the stdlib would first mean agreement on what such a stdlib should actually contain and look like, and this has a real risk of ending up in C++ Commitee style busywork (e.g. lots of activity with little to show for).