Command line parameters with VAX C?

[Martin v.d. Boogaard]

There are two ways to do the job. 

  1. Use argc and argv like you do on any other system. You saw that you can't
     type 

       RUN MYCODE PAR1 PAR2 <ret>

     because RUN expects only the name of the executable it should load. The 
     simple solution is to define (e.g. in LOGIN.COM)

       MYC*ODE :== $MYCODE <ret>

     which enables you to simply enter

       MYCODE PAR1 PAR2 <ret>

  2. The complicated way is to use the Command Definition Utility (CDU) to
     install a command MYCODE that takes two parameters and runs MYCODE.EXE .
     You can specify default values and options and check whether parameter
     values are filenames or numbers etc.  I use this to parse command
     line parameters to Pascal code because in VAX Pascal there is no such
     thing as argv . You have to use the routines CLI$PRESENT and CLI$GET_VALUE
     to find out about the values of your command line parameters. Off course
     the parameters off these system routines are passed by means of the usual
     string descriptor, which means you'll have to define a structure to match
     the VMS definition off this descriptor.

Solution #1 is quick and will solve many problems, #2 is very non-portable,
rather time consuming, but is to be preferred if you don't want your code to 
do the initial parameter checking.

Contact me directly if you need examples of the use of CDU or the application
of CLI$... 


Martin J. van den Boogaard          
                                        
Dept. of Atomic & Interface Physics, Rijksuniversiteit, Utrecht

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