albaugh@dms.UUCP (Mike Albaugh) (11/01/90)
From article <1990Oct26.211532.27626@unislc.uucp>, by ttobler@unislc.uucp (Trent Tobler): > From article <3785@wb3ffv.ampr.org>, by wmark@wb3ffv.ampr.org (Mark Winsor): >> >> I need to write a C front end for a cobol application. The cobol programs >> will return a string that is the name of the next program to call which is >> representing a C function. I need a way to associate that string with the >> function address, anybody have any ideas? Please don't suggest I rewrite the >> application in C, time doesn't allow that option. >> > > I'm not sure I understand the question, but as I understand it, you require > a 'C' function to be associated with a string? If you can get that to a > 'C' string, you can use either an array or linked list of structures with > a string and a function pointer. Here is an examples, using arrays... Not to pick on Trent, and lord knows I am _not_ a COBOL guru, but I believe that this and the other similar responses miss the _intent_ of Mark's question. COBOL provides a standard way to "call" a function (which may be in another "module", or whatever their term) by name, sort or like exec*() in *nix, but with the syntax and semantics defined in the language, and with perhaps more guarantees. An implementation may or may not provide this feature, but if they do, they have to support specific semantics. I am not at all sure that *nix can provide this function at all, or that Mark is trying to do it on *nix, but if so he should ask on the unix groups, where variants of this question regularly come up in regard to dynamic loading of libraries and LISP implementations. The answer is typically "There is no portable way" (even portable across unices), but you can usually grub around in the symbol table if you know your a.out format and your binaries have not been stripped. In any case: 1) This is almost certainly an OS, rather than C question. 2) It is a whole lot of pain, and non-portable 3) Mark may not even be on unix, but there _may_ be an os-specific hack. Oh, yeah, the sub-set problem of when you have an exhaustive list of all possible function names is amenable to munging the various relevant files and then using the techniques discussed in this thread so far, but it can lead to huge binaries :-) Of course, he said "next program to call", so some lessons on exec* _may_ do the trick, but that's still more of an OS than C question. Mike | Mike Albaugh (albaugh@dms.UUCP || {...decwrl!pyramid!}weitek!dms!albaugh) | Atari Games Corp (Arcade Games, no relation to the makers of the ST) | 675 Sycamore Dr. Milpitas, CA 95035 voice: (408)434-1709 | The opinions expressed are my own (Boy, are they ever)