Re: Blobs: How to tell when I retrieved a null blob

>From: Jacob Salomon <jake@apparel.net> >Date: Fri, 14 Feb 1997 10:23:52 GMT >X-Informix-List-Id: <news.33919> > >> [...] drop into C (ESQL/C) code passing the blob (by reference, not >> value!) as an argument, and therefore using poplocator() in the C >> code [...] > >You have, however, just opened another can of worms, worthy of a >separate thread: How would I pass a blob locator structure to a C >function by reference? I was never aware of any syntax for doing this. You can't avoid doing this -- when you pass a blob into an I4GL function, it is passed by reference, not by value (as everything else is). In the C code, there is a poplocator() call to get the locator: /* In fglsys.h */ extern void poplocator(loc_t **p); Note that you pass the address of a pointer to a locator structure: i4gl_play_with_blob(int i) { loc_t *blob; if (i != 1) fgl_fatal("i4gl_play_with_blob", 1, -1318); poplocator(&blob); ... } There is no way to return a blob -- there is no retlocator() call! Yours, Jonathan Leffler (johnl@informix.com) #include <disclaimer.h>