FWIW, COBOL can now call by value, if desired.
given: int cfunc (int x, double x, struct t *p); do this: call 'cfunc' using value cobol-fullword cobol-double reference cobol-structure returning ret-fullword Frank >________________________________ >From: Bernd Oppolzer <[email protected]> >To: [email protected] >Sent: Sunday, November 6, 2011 1:10 PM >Subject: Re: C newbie - pass a LDAP handle out to calling routine > >When calling C routines from other languages like COBOL or PL/1 (or FORTRAN), >you have to take into account that in C the parameters are passed "by value", >whereas >the other languages pass them "by reference", that is, addresses of the >variables. > >The solution is simple: to construct your C routines so that they can be >called from >other languages, put a star on every parameter, so that C expects pointers >instead >of values. Of course, when accessing the parameters inside the C functions, >you have to specify the stars, too. > >that is: > >int cfunc (int *x, double *x, struct type *p, ..); > >Furthermore, the result type should be int, so that other languages can read >the >return code from the C function result. > >If the parameter type is pointer, you need two stars, of course (that was your >point). > >Of course, this does not solve all the problems. You have still the issue with >char strings, >which are in fact vectors of single chars, so there is already a star. And you >need to >unterstand that when passing vectors as parameter, you normally pass the >starting address. > >And, with languages like PL/1, you have the locator/descriptor problem. But >that's >another topic and has nothing to do with C. > >Kind regards > >Bernd > > > >Am 06.11.2011 20:08, schrieb Gibney, Dave: >> With the assistance of several folks over on MVS-OE, I solved my problem. It >> is clear here that I did fail in the original question to be clear enough >> that my driving program is not C. The whole intent was to be able to pass >> that address from ldap_init back out to the non C driver so that it could be >> reused by the thousands of calls. The solution was: extern int ret2nat (int >> *back_value, LDAP **ld, char *msg) This pointer to a pointer format allows >> the fullword in the calling non C program hold the LDAP handle from call to >> call. > >---------------------------------------------------------------------- >For IBM-MAIN subscribe / signoff / archive access instructions, >send email to [email protected] with the message: GET IBM-MAIN INFO >Search the archives at http://bama.ua.edu/archives/ibm-main.html > > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
