Topic drift:
This is somehow easy from PL/1, for some reasons:
a) parameters to external functions can be defined in PL/1 to be
passed using NODESCRIPTOR and BYVALUE, so that the mechanisms
perfectly match the C mechanisms
b) PL/1 has a datatype CHAR (x) VARYINGZ (no typo), which means:
variable length, the length is designated by a terminating hex zero byte,
which again matches perfectly the C paradigm. This is superior to C,
because such a variable is known to have the hex zero before byte X.
CHAR (10) VARZ in fact has 11 bytes. The normal PL/1 functions like
LENGTH and SUBSTR work on VARZ like on normal VAR fields.
This said: some of the examples in the PL/1 reference and user's guide
show how to call C library functions from PL/1, which is a no-brainer.
Kind regards
Bernd
Am 06.04.2017 um 19:52 schrieb John McKown:
This is just a curiosity poll on my part. I'm wondering if anyone out there
has ever really used any C standard library routines (versus user written
code) in a COBOL program. I know that many may wonder "Why? What do I get
out of it." IMO, there are some useful routines in the standard C library
which could be used in COBOL.
One in particular which shows up quickly is the C language "cuserid()"
function. It will return the RACF id under which the program is running.
Now, since cuserid() plops a LOW-VALUE as an end-of-string delimiter, that
needs to be taken into consideration. Something like the following worked
for me:
01 USERID-PLUS-1
05 USERID PIC X(8).
05 FILLER PIC X.
01 CUSERID-POINTER POINTER.
CALL 'CUSERID' USING USERID-PLUS-1.
as did
CALL 'CUSERID' USING USERID-PLUS-1
RETURNING CUSERID-POINTER.
But this latter is unnecessary since the ID will be in USERID. But it might
have a LOW-VALUE, so it is better to do a MOVE SPACES TO USERID before the
CALL and a INSPECT USERID REPLACING LOW-VALUES BY SPACES after the call.
There are a lot more "interesting" C library functions which might be
useful. Such as the regular expression library for advanced text scanning
(OK, not a big COBOL thing). How about __get_cpuid() to get the CPU id of
the processor you're running on? DES encryption of data? The sprintf()
function to create a nicely formatted human readable message easily (not a
lot of space padding) although STRING might do this as well. On older
compilers, use the "calloc()" and "malloc()" function to get dynamic
storage areas to map with the LINKAGE SECTION. How about using "popen()" to
fire up a UNIX process to do some work for you?
Well, I'm going nutso again.
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