snprintf() confusion

snprintf() confusion

Posted Feb 7, 2004 18:09 UTC (Sat) by giraffedata (subscriber, #1954)
In reply to: snprintf() confusion by ThePythonicCow
Parent article: snprintf() confusion

it's not like printf has a choice of two possible lengths to choose from. It writes whatever it has format for, and counts it all (or SEGV's trying).

OK, I see in the printf case, a partial write isn't practical. But it doesn't really weaken the argument that printf is an I/O routine, and so it is natural to follow the pattern of write() and fwrite() and return the number of bytes written.

The leap from there to snprintf() is a lot more obvious when you include the sprintf() step. sprintf(), derived from printf(), quite naturally returns the number of characters formatted, just like printf(). And it's a very useful value, too. snprintf() was derived from sprintf(), and merely adds a constraint on the length; If you're going to drop it in to replace a dangerous sprintf(), you clearly want it to do the same as sprintf() and return the number of characters formatted.

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