As far as I can tell, stdio.h will generate declaration for snprintf if __IFS_IO__ is not defined. If it is defined, you are supposed to include ifs.h which will generate it. Alexei Pytel always speaking only for myself "We have all reasons to assume that our assumptions are not unreasonable." Brian Lewis <bsl04@xxxxxxxx> Sent by: c400-l-bounces+pytel=us.ibm.com@xxxxxxxxxxxx 07/28/2006 09:12 PM Please respond to C programming iSeries / AS400 <c400-l@xxxxxxxxxxxx> To c400-l@xxxxxxxxxxxx cc Subject [C400-L] function prototypes The V5R2 C compiler seems to be acting a little weirdly with regard to function prototypes. For example, I include stdio.h for snprintf. Member STDIO in QSYSINC/H contains the snprintf prototype. I'm using LANGLVL *EXTENDED. Even so, the compiler complains that it can't find the prototype for snprintf.