| Re: Calling External programm [message #1353] |
Thu, 04 November 1993 10:49 |
thompson
Messages: 584
Registered: August 1991
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Senior Member |
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estevez@atp3100.tuwien.ac.at (Ernesto Estevez) writes:
> Hi there>
> Im having some problems with the compiling, linking and setup of a C procedure to
> be used in IDL running in a VMS.
> -In my IDL User guide manual says that once you compiled your programm you should link it with the following statement
> MY_PRG : My programm
> $LINK MY_PRG, SYS$INPUT/OPT/SHARE
> well it hangs up, waiting for something.
What you need to do at that point is to type in the next line in the manual
which reads
UNIVERSAL = MY_AVG
for the particular example they're showing. If you're actually doing it at the
terminal, instead of from a command file, then you'll want to enter that line,
hit carriage return, and then control-Z to signal to the computer that the
input is done. Alternatively, you can put the UNIVERSAL line in a text file,
and substitute the name of this file for SYS$INPUT in the above command.
> -The second question is, can I have more than a function in my file, how things change then.
I think the only change is that each function would then have a separate
UNIVERSAL line associated with it. I think there's something you have to worry
about when you have common blocks in the FORTRAN procedures, but I don't
offhand remember what it was.
> -Finally, how is the parameter passing for a C function.
There is information on CALL_EXTERNAL in both the User's Guide and in the
Reference Guide. Essentially, you call C functions the same as FORTRAN
routines but there is an extra VALUE keyword to allow you to handle cases where
variables need to be passed by value. See the Reference Guide for more
information.
Bill Thompson
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